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Effects of the Social Environment and Stress on Glucocorticoid Receptor Gene Methylation: A Systematic Review

  • Gustavo Turecki
    Correspondence
    Address correspondence to Gustavo Turecki, M.D., Ph.D., Douglas Mental Health University Institute, McGill Group for Suicide Studies, 6875 Lasalle Boulevard, Montreal, QC H4H 1R3, Canada
    Affiliations
    Douglas Mental Health University Institute, McGill Group for Suicide Studies, and Ludmer Centre for Neuroinformatics and Mental Health, Department of Psychiatry, McGill University, Montreal, Canada
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  • Michael J. Meaney
    Affiliations
    Douglas Mental Health University Institute, McGill Group for Suicide Studies, and Ludmer Centre for Neuroinformatics and Mental Health, Department of Psychiatry, McGill University, Montreal, Canada
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Published:December 12, 2014DOI:https://doi.org/10.1016/j.biopsych.2014.11.022

      Abstract

      The early-life social environment can induce stable changes that influence neurodevelopment and mental health. Research focused on early-life adversity revealed that early-life experiences have a persistent impact on gene expression and behavior through epigenetic mechanisms. The hypothalamus-pituitary-adrenal axis is sensitive to changes in the early-life environment that associate with DNA methylation of a neuron-specific exon 17 promoter of the glucocorticoid receptor (GR) (Nr3c1). Since initial findings were published in 2004, numerous reports have investigated GR gene methylation in relationship to early-life experience, parental stress, and psychopathology. We conducted a systematic review of this growing literature, which identified 40 articles (13 animal and 27 human studies) published since 2004. The majority of these examined the GR exon variant 1F in humans or the GR17 in rats, and 89% of human studies and 70% of animal studies of early-life adversity reported increased methylation at this exon variant. All the studies investigating exon 1F/17 methylation in conditions of parental stress (one animal study and seven human studies) also reported increased methylation. Studies examining psychosocial stress and psychopathology had less consistent results, with 67% of animal studies reporting increased exon 17 methylation and 17% of human studies reporting increased exon 1F methylation. We found great consistency among studies investigating early-life adversity and the effect of parental stress, even if the precise phenotype and measures of social environment adversity varied among studies. These results are encouraging and warrant further investigation to better understand correlates and characteristics of these associations.

      Keywords

      There is substantial theoretical and empirical research supporting an association between early-life environmental adversity and poor lifetime mental health outcomes (
      • Evans E.
      • Hawton K.
      • Rodham K.
      Suicidal phenomena and abuse in adolescents: A review of epidemiological studies.
      ,
      • Ystgaard M.
      • Hestetun I.
      • Loeb M.
      • Mehlum L.
      Is there a specific relationship between childhood sexual and physical abuse and repeated suicidal behavior?.
      ,
      • Gilbert R.
      • Widom C.S.
      • Browne K.
      • Fergusson D.
      • Webb E.
      • Janson S.
      Burden and consequences of child maltreatment in high-income countries.
      ,
      • Collishaw S.
      • Pickles A.
      • Messer J.
      • Rutter M.
      • Shearer C.
      • Maughan B.
      Resilience to adult psychopathology following childhood maltreatment: Evidence from a community sample.
      ,
      • McLaughlin K.A.
      • Green J.G.
      • Gruber M.J.
      • Sampson N.A.
      • Zaslavsky A.M.
      • Kessler R.C.
      Childhood adversities and adult psychiatric disorders in the national comorbidity survey replication II: Associations with persistence of DSM-IV disorders.
      ,
      • Edwards V.J.
      • Holden G.W.
      • Felitti V.J.
      • Anda R.F.
      Relationship between multiple forms of childhood maltreatment and adult mental health in community respondents: Results from the adverse childhood experiences study.
      ,
      • Kessler R.C.
      • Davis C.G.
      • Kendler K.S.
      Childhood adversity and adult psychiatric disorder in the US National Comorbidity Survey.
      ,
      • Afifi T.O.
      • Enns M.W.
      • Cox B.J.
      • Asmundson G.J.
      • Stein M.B.
      • Sareen J.
      Population attributable fractions of psychiatric disorders and suicide ideation and attempts associated with adverse childhood experiences.
      ,
      • Widom C.S.
      Posttraumatic stress disorder in abused and neglected children grown up.
      ,
      • Widom C.S.
      • DuMont K.
      • Czaja S.J.
      A prospective investigation of major depressive disorder and comorbidity in abused and neglected children grown up.
      ,
      • Widom C.S.
      • White H.R.
      • Czaja S.J.
      • Marmorstein N.R.
      Long-term effects of child abuse and neglect on alcohol use and excessive drinking in middle adulthood.
      ,
      • Lansford J.E.
      • Dodge K.A.
      • Pettit G.S.
      • Bates J.E.
      • Crozier J.
      • Kaplow J.
      A 12-year prospective study of the long-term effects of early child physical maltreatment on psychological, behavioral, and academic problems in adolescence.
      ). A critical issue concerns the molecular mechanisms that account for such strong and long-lasting effects. There is evidence suggesting that early-life environmental influences induce changes in stable epigenetic states that regulate gene expression and ultimately complex neural functions. Thus, in both rodents and nonhuman primates, the early-life environment, including the quality of maternal care, regulates hypothalamus-pituitary-adrenal (HPA) axis function in adulthood (
      • Meaney M.J.
      Maternal care, gene expression, and the transmission of individual differences in stress reactivity across generations.
      ,
      • Levine A.
      • Cohen D.
      • Zadik Z.
      Urinary free cortisol values in children under stress.
      ,
      • Higley J.D.
      • Hasert M.F.
      • Suomi S.J.
      • Linnoila M.
      Nonhuman primate model of alcohol abuse: Effects of early experience, personality, and stress on alcohol consumption.
      ). Variations in the early social environment in rodents, modeled by maternal care, reveal profound and persistent alterations in gene expression and behavior that are mediated through epigenetic mechanisms, including changes in DNA methylation (
      • Weaver I.C.
      • Cervoni N.
      • Champagne F.A.
      • D׳Alessio A.C.
      • Sharma S.
      • Seckl J.R.
      • et al.
      Epigenetic programming by maternal behavior.
      ). The offspring of mothers with an increased frequency of pup licking/grooming (LG) (i.e., high LG mothers) show increased hippocampal glucocorticoid receptor (GR) (Nr3c1) expression, greater negative feedback regulation over hypothalamic corticotropin releasing factor (CRF), and more modest responses to stress compared with the offspring of low LG mothers (
      • Weaver I.C.
      • Cervoni N.
      • Champagne F.A.
      • D׳Alessio A.C.
      • Sharma S.
      • Seckl J.R.
      • et al.
      Epigenetic programming by maternal behavior.
      ,
      • Francis D.
      • Diorio J.
      • Liu D.
      • Meaney M.J.
      Nongenomic transmission across generations of maternal behavior and stress responses in the rat.
      ,
      • Liu D.
      • Diorio J.
      • Tannenbaum B.
      • Caldji C.
      • Francis D.
      • Freedman A.
      • et al.
      Maternal care, hippocampal glucocorticoid receptors, and hypothalamic-pituitary-adrenal responses to stress.
      ). Variations in maternal LG are linked to an epigenetic modification of a neuron-specific exon 17 GR promoter (
      • Weaver I.C.
      • Cervoni N.
      • Champagne F.A.
      • D׳Alessio A.C.
      • Sharma S.
      • Seckl J.R.
      • et al.
      Epigenetic programming by maternal behavior.
      ) such that increased maternal LG associates with decreased methylation of the exon 17 promoter and increased hippocampal GR expression.
      Subsequent studies in humans have expanded on the findings in rats. Accordingly, evidence for a long-term effect of early-life adversity (ELA) on the epigenetic state of the human genome was observed while investigating the methylation state of the GR gene in the hippocampus of individuals who died by suicide and had histories of child abuse (
      • McGowan P.O.
      • Sasaki A.
      • D׳Alessio A.C.
      • Dymov S.
      • Labonte B.
      • Szyf M.
      • et al.
      Epigenetic regulation of the glucocorticoid receptor in human brain associates with childhood abuse.
      ). ELA in humans reprograms the DNA methylation patterns of the GR gene exon 1F (GR1F; GR17 homologue in rats) promoter and decreases GR1F expression in the hippocampus of suicide completers with a history of child abuse compared with nonabused suicide completers and healthy control subjects (
      • McGowan P.O.
      • Sasaki A.
      • D׳Alessio A.C.
      • Dymov S.
      • Labonte B.
      • Szyf M.
      • et al.
      Epigenetic regulation of the glucocorticoid receptor in human brain associates with childhood abuse.
      ). An earlier study reported that children born to mothers with depression, irrespective of selective serotonin reuptake inhibitor use, exhibited higher GR1F methylation levels (
      • Oberlander T.F.
      • Weinberg J.
      • Papsdorf M.
      • Grunau R.
      • Misri S.
      • Devlin A.M.
      Prenatal exposure to maternal depression, neonatal methylation of human glucocorticoid receptor gene (NR3C1) and infant cortisol stress responses.
      ). Since these first reports, several studies have investigated the effect of environmental adversity, measured by ELA or exposure to parental stress, on GR gene methylation, using both animal models and human samples. These studies also used different designs, measures of adversity, and tissue samples and investigated methylation of diverse GR gene sequences. A growing number of studies have also been investigating the relationship between psychological stress or psychopathology and GR methylation. We conducted a systematic review of the growing literature investigating the relationship between environmental experience, stress, and GR gene methylation.

      Methods and Materials

      Study Identification

      We performed a search of association studies of the GR gene and DNA methylation. The primary search was carried out through the National Library of Medicine PubMed and a replication search was conducted through the Web of Knowledge database. The search included publications from 2004 up to July 2014 using the Weaver et al. (
      • Weaver I.C.
      • Cervoni N.
      • Champagne F.A.
      • D׳Alessio A.C.
      • Sharma S.
      • Seckl J.R.
      • et al.
      Epigenetic programming by maternal behavior.
      ) study as a starting point. The Medical Subject Headings terms used were “glucocorticoid receptor” or NR3C1 and epigenetics or “DNA methylation.” Additional articles were found by scanning the list of references of the original publications and review articles. Only articles in English and those investigating humans or other mammals were included.

      Study Selection

      The studies included in this systematic review met the following criteria: 1) use of a case-control or cohort design; 2) use of at least one analysis investigating DNA methylation of the GR gene in response to a change or perturbation in social environment; and 3) inclusion of studies independent from one another. Analyses based on the same set of data were excluded. In such cases, only the larger or more representative sample was retained. Studies in which a control group was absent also were not included.

      Data Extraction

      Information for each study was extracted based on nine variables: 1) species (human or nonhuman); 2) study (experimental) group; 3) sex; 4) sample size; 5) methodology (DNA methylation assessment); 6) tissue(s) investigated; 7) subject age at tissue collection; 8) region or first exon variant(s) investigated; and 9) effect on methylation (Tables S1–3). Studies were then grouped according to a broad classification of the study criteria and attributed to Tables S1, S2, or S3. Within each table, animal- and human-based studies were considered independently.

      Results

      There is a growing number of studies reporting changes in GR gene methylation in association with social environment and stress. Our search identified a total of 430 articles. Of these, 173 were review papers and were excluded. Another 210 articles were excluded due to lack of relevance to the topic of this review. Seven studies were removed because they were not independent, as they investigated samples for which results had been reported elsewhere. In all, 40 articles met all the specified criteria. These were then sorted based on whether they addressed GR gene methylation changes in response to ELA (22 articles; Table S1), parental stress (9 articles; Table S2), or psychological stress/psychopathology (11 articles; Table S3) [two studies were included in two tables because they addressed both ELA and psychological stress (
      • Steiger H.
      • Labonte B.
      • Groleau P.
      • Turecki G.
      • Israel M.
      Methylation of the glucocorticoid receptor gene promoter in bulimic women: Associations with borderline personality disorder, suicidality, and exposure to childhood abuse.
      ,
      • Desarnaud F.
      • Jakovcevski M.
      • Morellini F.
      • Schachner M.
      Stress downregulates hippocampal expression of the adhesion molecules NCAM and CHL1 in mice by mechanisms independent of DNA methylation of their promoters.
      )]. Within each table, the articles were further subdivided into animal studies, human studies using peripheral tissues, and human studies using central nervous system (CNS) tissue.

      Sample Type: Species and Tissues Studied

      Among the animal studies included, all used either rat (8 of 13 studies) or mouse (5 of 13 studies). All animal studies examined brain tissue, and one study compared brain tissue and fecal matter (
      • Liberman S.A.
      • Mashoodh R.
      • Thompson R.C.
      • Dolinoy D.C.
      • Champagne F.A.
      Concordance in hippocampal and fecal Nr3c1 methylation is moderated by maternal behavior in the mouse.
      ), while another compared brain tissue and adrenal tissue (
      • Witzmann S.R.
      • Turner J.D.
      • Meriaux S.B.
      • Meijer O.C.
      • Muller C.P.
      Epigenetic regulation of the glucocorticoid receptor promoter 1(7) in adult rats.
      ). The brain region studied varied, including cortical and subcortical regions.
      In the human studies, the majority of articles reported on GR gene methylation in peripheral tissues, where the term peripheral refers to tissues other than the CNS. In the human peripheral studies category, 20 of the 24 articles used blood tissue, while 2 used saliva (
      • Melas P.A.
      • Wei Y.
      • Wong C.C.
      • Sjoholm L.K.
      • Aberg E.
      • Mill J.
      • et al.
      Genetic and epigenetic associations of MAOA and NR3C1 with depression and childhood adversities.
      ,
      • Weder N.
      • Zhang H.
      • Jensen K.
      • Yang B.Z.
      • Simen A.
      • Jackowski A.
      • et al.
      Child abuse, depression, and methylation in genes involved with stress, neural plasticity, and brain circuitry.
      ), 1 used buccal epithelial cells (
      • Essex M.J.
      • Boyce W.T.
      • Hertzman C.
      • Lam L.L.
      • Armstrong J.M.
      • Neumann S.M.
      • Kobor M.S.
      Epigenetic vestiges of early developmental adversity: Childhood stress exposure and DNA methylation in adolescence.
      ), and 1 used placental tissue (
      • Conradt E.
      • Lester B.M.
      • Appleton A.A.
      • Armstrong D.A.
      • Marsit C.J.
      The roles of DNA methylation of NR3C1 and 11beta-HSD2 and exposure to maternal mood disorder in utero on newborn neurobehavior.
      ). Of the 3 studies examining brain tissue (the human central tissues category), all examined tissues from the limbic and cortical regions (
      • McGowan P.O.
      • Sasaki A.
      • D׳Alessio A.C.
      • Dymov S.
      • Labonte B.
      • Szyf M.
      • et al.
      Epigenetic regulation of the glucocorticoid receptor in human brain associates with childhood abuse.
      ,
      • Labonte B.
      • Yerko V.
      • Gross J.
      • Mechawar N.
      • Meaney M.J.
      • Szyf M.
      • Turecki G.
      Differential glucocorticoid receptor exon 1(B), 1(C), and 1(H) expression and methylation in suicide completers with a history of childhood abuse.
      ,
      • Alt S.R.
      • Turner J.D.
      • Klok M.D.
      • Meijer O.C.
      • Lakke E.A.
      • Derijk R.H.
      • Muller C.P.
      Differential expression of glucocorticoid receptor transcripts in major depressive disorder is not epigenetically programmed.
      ) and focused in particular on the hippocampus. In addition, Labonté et al. (
      • Labonte B.
      • Yerko V.
      • Gross J.
      • Mechawar N.
      • Meaney M.J.
      • Szyf M.
      • Turecki G.
      Differential glucocorticoid receptor exon 1(B), 1(C), and 1(H) expression and methylation in suicide completers with a history of childhood abuse.
      ) examined the anterior cingulate cortex, while Alt et al. (
      • Alt S.R.
      • Turner J.D.
      • Klok M.D.
      • Meijer O.C.
      • Lakke E.A.
      • Derijk R.H.
      • Muller C.P.
      Differential expression of glucocorticoid receptor transcripts in major depressive disorder is not epigenetically programmed.
      ) investigated the amygdala, inferior prefrontal gyrus, cingulate gyrus, and nucleus accumbens.

      GR Gene Region Examined

      The GR gene in humans and rodents consists of 11 exons including untranslated first exon variants (
      • McCormick J.A.
      • Lyons V.
      • Jacobson M.D.
      • Noble J.
      • Diorio J.
      • Nyirenda M.
      • et al.
      5׳-heterogeneity of glucocorticoid receptor messenger RNA is tissue specific: Differential regulation of variant transcripts by early-life events.
      ). Nine untranslated first exon variants, each possessing their own promoter region, have been identified in humans (1A, I, D, J, E, B, F, C, and H) and in rats (11, 4–11). We found significant heterogeneity in the reporting and identification of the specific regions of the first exon variants that were studied. Specifically, there was no consistency in how CpG sites were identified and labeled, making the determination of overlapping regions difficult. This made detecting consistency in findings at the sequence level among studies challenging. We compiled the sequence data that we were able to retrieve from information published in all the human studies and located the regions within the GR gene containing the first exon variants investigated (Figure S1 in Supplement 1).

      Early-Life Adversity

      Experimental Groups

      To ensure the maximum impact of the review and allow for the comparison of results, we carefully selected articles that used similar criteria to define ELA.
      In animal models, early-life experience was characterized by the use of maternal care models in six studies (
      • Weaver I.C.
      • Cervoni N.
      • Champagne F.A.
      • D׳Alessio A.C.
      • Sharma S.
      • Seckl J.R.
      • et al.
      Epigenetic programming by maternal behavior.
      ,
      • Liberman S.A.
      • Mashoodh R.
      • Thompson R.C.
      • Dolinoy D.C.
      • Champagne F.A.
      Concordance in hippocampal and fecal Nr3c1 methylation is moderated by maternal behavior in the mouse.
      ,
      • Weaver I.C.
      • Champagne F.A.
      • Brown S.E.
      • Dymov S.
      • Sharma S.
      • Meaney M.J.
      • Szyf M.
      Reversal of maternal programming of stress responses in adult offspring through methyl supplementation: Altering epigenetic marking later in life.
      ,
      • Henningsen K.
      • Dyrvig M.
      • Bouzinova E.V.
      • Christiansen S.
      • Christensen T.
      • Andreasen J.T.
      • et al.
      Low maternal care exacerbates adult stress susceptibility in the chronic mild stress rat model of depression.
      ,
      • Kosten T.A.
      • Huang W.
      • Nielsen D.A.
      Sex and litter effects on anxiety and DNA methylation levels of stress and neurotrophin genes in adolescent rats.
      ,
      • Kosten T.A.
      • Nielsen D.A.
      Litter and sex effects on maternal behavior and DNA methylation of the Nr3c1 exon 1 promoter gene in hippocampus and cerebellum.
      ) or maternal separation models in four studies (
      • Desarnaud F.
      • Jakovcevski M.
      • Morellini F.
      • Schachner M.
      Stress downregulates hippocampal expression of the adhesion molecules NCAM and CHL1 in mice by mechanisms independent of DNA methylation of their promoters.
      ,
      • Daniels W.M.
      • Fairbairn L.R.
      • van Tilburg G.
      • McEvoy C.R.
      • Zigmond M.J.
      • Russell V.A.
      • Stein D.J.
      Maternal separation alters nerve growth factor and corticosterone levels but not the DNA methylation status of the exon 1(7) glucocorticoid receptor promoter region.
      ,
      • Kember R.L.
      • Dempster E.L.
      • Lee T.H.
      • Schalkwyk L.C.
      • Mill J.
      • Fernandes C.
      Maternal separation is associated with strain-specific responses to stress and epigenetic alterations to Nr3c1, Avp, and Nr4a1 in mouse.
      ,
      • Kundakovic M.
      • Lim S.
      • Gudsnuk K.
      • Champagne F.A.
      Sex-specific and strain-dependent effects of early life adversity on behavioral and epigenetic outcomes.
      ).
      Human studies defined ELA as exposure to traumatic events in childhood, including emotional, physical, or sexual abuse; neglect; early parental death; and other traumatic events. All studies included subjects who had been exposed to childhood abuse, with variations in the type of abuse included. In addition, three studies included early parental death as a marker of ELA (
      • Melas P.A.
      • Wei Y.
      • Wong C.C.
      • Sjoholm L.K.
      • Aberg E.
      • Mill J.
      • et al.
      Genetic and epigenetic associations of MAOA and NR3C1 with depression and childhood adversities.
      ,
      • Tyrka A.R.
      • Price L.H.
      • Marsit C.
      • Walters O.C.
      • Carpenter L.L.
      Childhood adversity and epigenetic modulation of the leukocyte glucocorticoid receptor: Preliminary findings in healthy adults.
      ,
      • van der Knaap L.J.
      • Riese H.
      • Hudziak J.J.
      • Verbiest M.M.
      • Verhulst F.C.
      • Oldehinkel A.J.
      • van Oort F.V.
      Glucocorticoid receptor gene (NR3C1) methylation following stressful events between birth and adolescence. The TRAILS study.
      ).

      GR Region Studied

      The majority of studies included in this review examined exon 17 (10 of 10 animal studies) or exon 1F (10 of 12 human studies). One study also examined exon 1D, while two studies also examined exon 1B and 1C and three studies examined exon 1H. Of the 10 studies examining exon 17 and the 10 studies examining exon 1F, 9 and 6 studies, respectively, included examination of the binding site for the transcription factor NGFI-A (Egr-1, Zyf-268) (Table S1 and Figure S1 in Supplement 1), which regulates GR gene transcription (
      • McGowan P.O.
      • Sasaki A.
      • D׳Alessio A.C.
      • Dymov S.
      • Labonte B.
      • Szyf M.
      • et al.
      Epigenetic regulation of the glucocorticoid receptor in human brain associates with childhood abuse.
      ,
      • Weaver I.C.
      • D׳Alessio A.C.
      • Brown S.E.
      • Hellstrom I.C.
      • Dymov S.
      • Sharma S.
      • et al.
      The transcription factor nerve growth factor-inducible protein a mediates epigenetic programming: Altering epigenetic marks by immediate-early genes.
      ).

      Effect on Methylation

      As the majority of studies reported on exon 17/1F, we focused our comparisons on this particular variant. In the ELA group, all 10 animal studies examining GR gene methylation investigated exon 17, and 7 studies (70%) reported a significant increase in methylation in the exon 17 promoter, while 3 studies reported no change in exon 17 methylation status (
      • Desarnaud F.
      • Jakovcevski M.
      • Morellini F.
      • Schachner M.
      Stress downregulates hippocampal expression of the adhesion molecules NCAM and CHL1 in mice by mechanisms independent of DNA methylation of their promoters.
      ,
      • Henningsen K.
      • Dyrvig M.
      • Bouzinova E.V.
      • Christiansen S.
      • Christensen T.
      • Andreasen J.T.
      • et al.
      Low maternal care exacerbates adult stress susceptibility in the chronic mild stress rat model of depression.
      ,
      • Daniels W.M.
      • Fairbairn L.R.
      • van Tilburg G.
      • McEvoy C.R.
      • Zigmond M.J.
      • Russell V.A.
      • Stein D.J.
      Maternal separation alters nerve growth factor and corticosterone levels but not the DNA methylation status of the exon 1(7) glucocorticoid receptor promoter region.
      ). Of the 10 human studies examining exon 1F methylation, 9 reported increased promoter methylation with ELA (90%). Of these, one study reported increased methylation at CpG sites labeled by the authors as CpGs 3, 6, and 7 in the whole sample, while a socioeconomic-matched subsample exhibited a decrease in methylation level of a single CpG (CpG 2), located before the NFGI-A binding site (CpGs 3 and 4), in conjunction with increased methylation at CpGs 3, 5, and 6 (
      • Romens S.E.
      • McDonald J.
      • Svaren J.
      • Pollak S.D.
      Associations between early life stress and gene methylation in children [published online ahead of print July 24].
      ). One study reported no change in GR1F methylation status in response to ELA (
      • Steiger H.
      • Labonte B.
      • Groleau P.
      • Turecki G.
      • Israel M.
      Methylation of the glucocorticoid receptor gene promoter in bulimic women: Associations with borderline personality disorder, suicidality, and exposure to childhood abuse.
      ) (Figure 1). A single study reported on exon 1D methylation and found decreased methylation in blood samples of adolescents with early-life stress (
      • van der Knaap L.J.
      • Riese H.
      • Hudziak J.J.
      • Verbiest M.M.
      • Verhulst F.C.
      • Oldehinkel A.J.
      • van Oort F.V.
      Glucocorticoid receptor gene (NR3C1) methylation following stressful events between birth and adolescence. The TRAILS study.
      ). In addition, one study reported no change in methylation of exons 1B and 1C in peripheral tissues (
      • Steiger H.
      • Labonte B.
      • Groleau P.
      • Turecki G.
      • Israel M.
      Methylation of the glucocorticoid receptor gene promoter in bulimic women: Associations with borderline personality disorder, suicidality, and exposure to childhood abuse.
      ), while another found increased methylation in brain tissues of subjects with childhood abuse (
      • Labonte B.
      • Yerko V.
      • Gross J.
      • Mechawar N.
      • Meaney M.J.
      • Szyf M.
      • Turecki G.
      Differential glucocorticoid receptor exon 1(B), 1(C), and 1(H) expression and methylation in suicide completers with a history of childhood abuse.
      ). Three studies reported on the methylation status of exon 1H, with one study reporting no change (
      • Steiger H.
      • Labonte B.
      • Groleau P.
      • Turecki G.
      • Israel M.
      Methylation of the glucocorticoid receptor gene promoter in bulimic women: Associations with borderline personality disorder, suicidality, and exposure to childhood abuse.
      ), one study reporting increased methylation (
      • van der Knaap L.J.
      • Riese H.
      • Hudziak J.J.
      • Verbiest M.M.
      • Verhulst F.C.
      • Oldehinkel A.J.
      • van Oort F.V.
      Glucocorticoid receptor gene (NR3C1) methylation following stressful events between birth and adolescence. The TRAILS study.
      ), and one study reporting decreased methylation (
      • Labonte B.
      • Yerko V.
      • Gross J.
      • Mechawar N.
      • Meaney M.J.
      • Szyf M.
      • Turecki G.
      Differential glucocorticoid receptor exon 1(B), 1(C), and 1(H) expression and methylation in suicide completers with a history of childhood abuse.
      ). Additionally, one study reported decreased GR gene methylation but did not specify the region investigated (
      • Guillemin C.
      • Provencal N.
      • Suderman M.
      • Cote S.M.
      • Vitaro F.
      • Hallett M.
      • et al.
      DNA methylation signature of childhood chronic physical aggression in T cells of both men and women.
      ).
      Figure thumbnail gr1
      Figure 1Early-life adversity findings in animal and human studies. Significant findings reported from animal and human studies examining the effects of early-life adversity according to the NR3C1 first exon variant investigated. Publications are numbered according to their position in the reference list. Upward arrow indicates increased methylation, while downward arrow indicates decreased methylation. Results were reported as mean methylation of the region investigated unless otherwise indicated by the footnotes. a, glucocorticoid receptor gene CpG methylation undetectable in all conditions; b, hippocampus only at CpG 1 and 2, NGFI-A site; ↑ methylation correlated to decreased nursing frequency; c, CpG 35 (NGFI-A site is CpG 37 and 38); d, for 6 promoter-associated CpGs; e, CpG 6 and 8, ↑ methylation of both abused and nonabused compared with control subjects; CpG11, ↓ methylation of both abused and nonabused compared with control subjects; hippocampus only; f, CpGs 8, 9, 12, and 13; hippocampus only; g, hippocampus only; h, cerebellum; CpGs 127 and 10; single sex male animals and mixed-litter female animals compared with mixed-sex male animals; i, CpG 13,14, 17, DBA/2J only; j, C57BL/6J, hippocampus and male animals only; k, CpG 1 and 3 only (NGFI-A site is CpG 3 and 4); l, repeated exposure to nonphysical, nonsexual abuse; m, single exposure to sexual abuse only; n, ↓ CpG 2 in subset of subjects only; ↑ CpGs 3, 6, and 7 whole sample and 3, 5, and 6 in subset; NGFI-A site at CpG 3 and 4; o, CpGs at −99 and −57 for all female animals in hippocampus; CpGs −118, −116, −114 in single-sex female animals in nucleus accumbens; CpG −57 in male vs. female animals in nucleus accumbens; p, reached significance with physical abuse, trend with emotional neglect.

      Parental Stress

      Experimental Groups

      One animal study (
      • Mueller B.R.
      • Bale T.L.
      Sex-specific programming of offspring emotionality after stress early in pregnancy.
      ) used a variety of nonpain-inducing, nonhabituating stressors over the course of 7 days to stress mouse dams. Human studies examined the methylation status of children of women who had experienced anxiety and mood disorders (
      • Oberlander T.F.
      • Weinberg J.
      • Papsdorf M.
      • Grunau R.
      • Misri S.
      • Devlin A.M.
      Prenatal exposure to maternal depression, neonatal methylation of human glucocorticoid receptor gene (NR3C1) and infant cortisol stress responses.
      ,
      • Conradt E.
      • Lester B.M.
      • Appleton A.A.
      • Armstrong D.A.
      • Marsit C.J.
      The roles of DNA methylation of NR3C1 and 11beta-HSD2 and exposure to maternal mood disorder in utero on newborn neurobehavior.
      ), pregnancy-related anxiety (
      • Hompes T.
      • Izzi B.
      • Gellens E.
      • Morreels M.
      • Fieuws S.
      • Pexsters A.
      • et al.
      Investigating the influence of maternal cortisol and emotional state during pregnancy on the DNA methylation status of the glucocorticoid receptor gene (NR3C1) promoter region in cord blood.
      ), violence (
      • Radtke K.M.
      • Ruf M.
      • Gunter H.M.
      • Dohrmann K.
      • Schauer M.
      • Meyer A.
      • Elbert T.
      Transgenerational impact of intimate partner violence on methylation in the promoter of the glucocorticoid receptor.
      ), or war stress (
      • Mulligan C.J.
      • D׳Errico N.C.
      • Stees J.
      • Hughes D.A.
      Methylation changes at NR3C1 in newborns associate with maternal prenatal stress exposure and newborn birth weight.
      ,
      • Perroud N.
      • Rutembesa E.
      • Paoloni-Giacobino A.
      • Mutabaruka J.
      • Mutesa L.
      • Stenz L.
      • et al.
      The Tutsi genocide and transgenerational transmission of maternal stress: Epigenetics and biology of the HPA axis.
      ) during pregnancy. Another study examined the effects of parental stress on GR gene methylation in adolescence (
      • Essex M.J.
      • Boyce W.T.
      • Hertzman C.
      • Lam L.L.
      • Armstrong J.M.
      • Neumann S.M.
      • Kobor M.S.
      Epigenetic vestiges of early developmental adversity: Childhood stress exposure and DNA methylation in adolescence.
      ), and one additional study studied the methylation patterns of individuals whose parents had experienced war but not necessarily during pregnancy (
      • Yehuda R.
      • Daskalakis N.P.
      • Lehrner A.
      • Desarnaud F.
      • Bader H.N.
      • Makotkine I.
      • et al.
      Influences of maternal and paternal PTSD on epigenetic regulation of the glucocorticoid receptor gene in Holocaust survivor offspring.
      ) (Table S2).

      GR Gene Region

      Most studies in this group examined exon 17 (for the animal study) or exon 1F (7 of 8 human studies), and the sites analyzed spanned the NFGI-A binding site. One study also examined exons 1D and 1B (
      • Hompes T.
      • Izzi B.
      • Gellens E.
      • Morreels M.
      • Fieuws S.
      • Pexsters A.
      • et al.
      Investigating the influence of maternal cortisol and emotional state during pregnancy on the DNA methylation status of the glucocorticoid receptor gene (NR3C1) promoter region in cord blood.
      ).

      Effect on Methylation

      Interestingly, all eight studies investigating exon 1F/17 (including the animal study) reported an increased methylation of exon 17/1F in offspring of parentally stressed individuals (Figure 2). Of these, two studies also reported decreased methylation at specific CpG sites and in particular conditions. For example, Hompes et al. (
      • Hompes T.
      • Izzi B.
      • Gellens E.
      • Morreels M.
      • Fieuws S.
      • Pexsters A.
      • et al.
      Investigating the influence of maternal cortisol and emotional state during pregnancy on the DNA methylation status of the glucocorticoid receptor gene (NR3C1) promoter region in cord blood.
      ) reported a decreased methylation at a position labeled by the authors as CpG 36 (near the NGFI-A binding site) only during trimesters 1 and 2 in women reporting a fear of changes associated with their pregnancy. Additionally, in the study of the offspring of Holocaust survivors, maternal experience of Holocaust was associated with decreased methylation of exon 1F, while paternal experience of Holocaust was associated with increased exon 1F methylation (
      • Yehuda R.
      • Daskalakis N.P.
      • Lehrner A.
      • Desarnaud F.
      • Bader H.N.
      • Makotkine I.
      • et al.
      Influences of maternal and paternal PTSD on epigenetic regulation of the glucocorticoid receptor gene in Holocaust survivor offspring.
      ). Of note, the study investigating Holocaust survivors recruited participants born after the end of World War II and therefore did not necessarily include mothers who experienced stress during pregnancy but rather before pregnancy. Only one study examined other exon 1 variants, reporting increased methylation of exon 1D in the children of women experiencing fear of delivery in all trimesters or fear of the integrity of the baby in the first trimester and decreased methylation of exon 1B in the children of women with fear of delivery (
      • Hompes T.
      • Izzi B.
      • Gellens E.
      • Morreels M.
      • Fieuws S.
      • Pexsters A.
      • et al.
      Investigating the influence of maternal cortisol and emotional state during pregnancy on the DNA methylation status of the glucocorticoid receptor gene (NR3C1) promoter region in cord blood.
      ). Finally, an additional study investigated a single CpG located downstream of the 1H promoter (in the gene body) and found no change in methylation status (
      • Essex M.J.
      • Boyce W.T.
      • Hertzman C.
      • Lam L.L.
      • Armstrong J.M.
      • Neumann S.M.
      • Kobor M.S.
      Epigenetic vestiges of early developmental adversity: Childhood stress exposure and DNA methylation in adolescence.
      ).
      Figure thumbnail gr2
      Figure 2Parental stress findings in animal and human studies. Significant findings reported from animal and human studies examining the effects of parental stress according to the NR3C1 first exon variant investigated. Publications are numbered according to their position in the reference list. Upward arrow indicates increased methylation, while downward arrow indicates decreased methylation. Results were reported as mean methylation of the region investigated unless otherwise indicated by the footnotes. a, CpG 1–3, NFGI-A site; b, indicates a sampling downstream of region 1H, within the gene body; c, CpG 2, depression only; d, early gestation group only; CpGs −523 and −496; e, CpG 12 and 13 with fear of delivery all trimesters; CpG 25 and 28 with fear of integrity of the baby trimester 1; f, CpG 6 with fear of delivery; g, site- and parameter-specific: CpG 38/39 (near NGFI-A site) ↓ with fear of changes trimesters 1 and 2; CpG 36 ↑ with fear of integrity trimesters 1 and 2; CpG 36 ↑ with fear of delivery trimester 3; h, total region for children; CpGs 1, 5, and 8 for mothers; i, ↑ methylation with paternal posttraumatic stress disorder only in the absence of maternal posttraumatic stress disorder.

      Psychological Stress/Psychopathology

      Experimental Groups

      Three animal studies used acute or chronic stress models to assess the impact of social stressors on GR gene methylation (
      • Desarnaud F.
      • Jakovcevski M.
      • Morellini F.
      • Schachner M.
      Stress downregulates hippocampal expression of the adhesion molecules NCAM and CHL1 in mice by mechanisms independent of DNA methylation of their promoters.
      ,
      • Witzmann S.R.
      • Turner J.D.
      • Meriaux S.B.
      • Meijer O.C.
      • Muller C.P.
      Epigenetic regulation of the glucocorticoid receptor promoter 1(7) in adult rats.
      ,
      • Tran L.
      • Chaloner A.
      • Sawalha A.H.
      • Greenwood Van-Meerveld B.
      Importance of epigenetic mechanisms in visceral pain induced by chronic water avoidance stress.
      ). In addition, eight studies examined the effects of psychopathologies on human GR gene methylation. Specifically, studies included response to stress (
      • de Rooij S.R.
      • Costello P.M.
      • Veenendaal M.V.
      • Lillycrop K.A.
      • Gluckman P.D.
      • Hanson M.A.
      • et al.
      Associations between DNA methylation of a glucocorticoid receptor promoter and acute stress responses in a large healthy adult population are largely explained by lifestyle and educational differences.
      ), borderline personality disorder (
      • Dammann G.
      • Teschler S.
      • Haag T.
      • Altmuller F.
      • Tuczek F.
      • Dammann R.H.
      Increased DNA methylation of neuropsychiatric genes occurs in borderline personality disorder.
      ), bulimia nervosa (
      • Steiger H.
      • Labonte B.
      • Groleau P.
      • Turecki G.
      • Israel M.
      Methylation of the glucocorticoid receptor gene promoter in bulimic women: Associations with borderline personality disorder, suicidality, and exposure to childhood abuse.
      ), posttraumatic stress disorder (
      • Yehuda R.
      • Daskalakis N.P.
      • Desarnaud F.
      • Makotkine I.
      • Lehrner A.L.
      • Koch E.
      • et al.
      Epigenetic biomarkers as predictors and correlates of symptom improvement following psychotherapy in combat veterans with PTSD.
      ,
      • Yehuda R.
      • Flory J.D.
      • Bierer L.M.
      • Henn-Haase C.
      • Lehrner A.
      • Desarnaud F.
      • et al.
      Lower methylation of glucocorticoid receptor gene promoter 1 in peripheral blood of veterans with posttraumatic stress disorder.
      ,
      • Labonte B.
      • Azoulay N.
      • Yerko V.
      • Turecki G.
      • Brunet A.
      Epigenetic modulation of glucocorticoid receptors in posttraumatic stress disorder.
      ), and depression (
      • Alt S.R.
      • Turner J.D.
      • Klok M.D.
      • Meijer O.C.
      • Lakke E.A.
      • Derijk R.H.
      • Muller C.P.
      Differential expression of glucocorticoid receptor transcripts in major depressive disorder is not epigenetically programmed.
      ,
      • Na K.S.
      • Chang H.S.
      • Won E.
      • Han K.M.
      • Choi S.
      • Tae W.S.
      • et al.
      Association between glucocorticoid receptor methylation and hippocampal subfields in major depressive disorder.
      ) (Table S3).

      GR Gene Region

      Most studies in this group examined exon 17 (three animal studies) or exon 1F (six of the eight human studies). In addition, three studies examined exon 1B (
      • Steiger H.
      • Labonte B.
      • Groleau P.
      • Turecki G.
      • Israel M.
      Methylation of the glucocorticoid receptor gene promoter in bulimic women: Associations with borderline personality disorder, suicidality, and exposure to childhood abuse.
      ,
      • Alt S.R.
      • Turner J.D.
      • Klok M.D.
      • Meijer O.C.
      • Lakke E.A.
      • Derijk R.H.
      • Muller C.P.
      Differential expression of glucocorticoid receptor transcripts in major depressive disorder is not epigenetically programmed.
      ,
      • Labonte B.
      • Azoulay N.
      • Yerko V.
      • Turecki G.
      • Brunet A.
      Epigenetic modulation of glucocorticoid receptors in posttraumatic stress disorder.
      ), two studies examined exons 1C and 1H (
      • Steiger H.
      • Labonte B.
      • Groleau P.
      • Turecki G.
      • Israel M.
      Methylation of the glucocorticoid receptor gene promoter in bulimic women: Associations with borderline personality disorder, suicidality, and exposure to childhood abuse.
      ,
      • Labonte B.
      • Azoulay N.
      • Yerko V.
      • Turecki G.
      • Brunet A.
      Epigenetic modulation of glucocorticoid receptors in posttraumatic stress disorder.
      ), and one study examined exons 1J and 1E (
      • Alt S.R.
      • Turner J.D.
      • Klok M.D.
      • Meijer O.C.
      • Lakke E.A.
      • Derijk R.H.
      • Muller C.P.
      Differential expression of glucocorticoid receptor transcripts in major depressive disorder is not epigenetically programmed.
      ). Of the eight studies examining exon 17/1F, six studies specified that they included examination of the binding site for NGFI-A.

      Effect on Methylation

      Two of the three animal studies included in this group reported increased exon 17 methylation in stressed animals, but studies reporting on human psychological stress/psychopathology had more varied results (Figure 3). One study reported increased methylation of exon 1F (
      • Dammann G.
      • Teschler S.
      • Haag T.
      • Altmuller F.
      • Tuczek F.
      • Dammann R.H.
      Increased DNA methylation of neuropsychiatric genes occurs in borderline personality disorder.
      ), while three studies reported no change (
      • Steiger H.
      • Labonte B.
      • Groleau P.
      • Turecki G.
      • Israel M.
      Methylation of the glucocorticoid receptor gene promoter in bulimic women: Associations with borderline personality disorder, suicidality, and exposure to childhood abuse.
      ,
      • Alt S.R.
      • Turner J.D.
      • Klok M.D.
      • Meijer O.C.
      • Lakke E.A.
      • Derijk R.H.
      • Muller C.P.
      Differential expression of glucocorticoid receptor transcripts in major depressive disorder is not epigenetically programmed.
      ,
      • Yehuda R.
      • Daskalakis N.P.
      • Desarnaud F.
      • Makotkine I.
      • Lehrner A.L.
      • Koch E.
      • et al.
      Epigenetic biomarkers as predictors and correlates of symptom improvement following psychotherapy in combat veterans with PTSD.
      ) and two reported decreased methylation (
      • Yehuda R.
      • Flory J.D.
      • Bierer L.M.
      • Henn-Haase C.
      • Lehrner A.
      • Desarnaud F.
      • et al.
      Lower methylation of glucocorticoid receptor gene promoter 1 in peripheral blood of veterans with posttraumatic stress disorder.
      ,
      • Na K.S.
      • Chang H.S.
      • Won E.
      • Han K.M.
      • Choi S.
      • Tae W.S.
      • et al.
      Association between glucocorticoid receptor methylation and hippocampal subfields in major depressive disorder.
      ). Among the other exon variants examined, there was no consensus on the effects of psychological stress/psychopathology on methylation status. Exons 1J and 1E showed no change in methylation, exon 1B was unchanged in two studies (
      • Steiger H.
      • Labonte B.
      • Groleau P.
      • Turecki G.
      • Israel M.
      Methylation of the glucocorticoid receptor gene promoter in bulimic women: Associations with borderline personality disorder, suicidality, and exposure to childhood abuse.
      ,
      • Alt S.R.
      • Turner J.D.
      • Klok M.D.
      • Meijer O.C.
      • Lakke E.A.
      • Derijk R.H.
      • Muller C.P.
      Differential expression of glucocorticoid receptor transcripts in major depressive disorder is not epigenetically programmed.
      ) and had decreased methylation in one study (
      • Labonte B.
      • Azoulay N.
      • Yerko V.
      • Turecki G.
      • Brunet A.
      Epigenetic modulation of glucocorticoid receptors in posttraumatic stress disorder.
      ), and exon 1C was hypermethylated in one study (
      • Steiger H.
      • Labonte B.
      • Groleau P.
      • Turecki G.
      • Israel M.
      Methylation of the glucocorticoid receptor gene promoter in bulimic women: Associations with borderline personality disorder, suicidality, and exposure to childhood abuse.
      ), hypomethylated in one study (
      • Labonte B.
      • Azoulay N.
      • Yerko V.
      • Turecki G.
      • Brunet A.
      Epigenetic modulation of glucocorticoid receptors in posttraumatic stress disorder.
      ), and unchanged in one study (
      • de Rooij S.R.
      • Costello P.M.
      • Veenendaal M.V.
      • Lillycrop K.A.
      • Gluckman P.D.
      • Hanson M.A.
      • et al.
      Associations between DNA methylation of a glucocorticoid receptor promoter and acute stress responses in a large healthy adult population are largely explained by lifestyle and educational differences.
      ). Finally, exon 1H was hypomethylated in one study (
      • Steiger H.
      • Labonte B.
      • Groleau P.
      • Turecki G.
      • Israel M.
      Methylation of the glucocorticoid receptor gene promoter in bulimic women: Associations with borderline personality disorder, suicidality, and exposure to childhood abuse.
      ) and unchanged in another (
      • Labonte B.
      • Azoulay N.
      • Yerko V.
      • Turecki G.
      • Brunet A.
      Epigenetic modulation of glucocorticoid receptors in posttraumatic stress disorder.
      ).
      Figure thumbnail gr3
      Figure 3Psychological stress/psychopathology findings in animal and human studies. Significant findings reported from animal and human studies examining the effects of psychological stress/psychopathology according to the NR3C1 first exon variant investigated. Publications are numbered according to their position in the reference list. Upward arrow indicates increased methylation, while downward arrow indicates decreased methylation. Results were reported as mean methylation of the region investigated unless otherwise indicated by the footnotes. a, CpGs 10 and 21; bulimia nervosa vs. no eating disorder; b, in bulimia nervosa + borderline personality disorder vs. bulimia nervosa no borderline personality disorder/no eating disorder; c, no detectable methylation on NR3C1 CpGs; d, acute stress group—↑ methylation at several CpG sites in hippocampus only; chronic stress group—↑ methylation in response to psychosocial stress in adrenal and pituitary, ↑ methylation in adrenal and ↓ methylation in the pituitary in response to restraint stress; e, no change over time and no difference between responders and nonresponders; f, CpGs 3 and 4.

      Conclusions

      Since the publication of Weaver et al. (
      • Weaver I.C.
      • Cervoni N.
      • Champagne F.A.
      • D׳Alessio A.C.
      • Sharma S.
      • Seckl J.R.
      • et al.
      Epigenetic programming by maternal behavior.
      ), there has been a surge in interest in GR gene methylation changes associated with altered social environment and stress, as evidenced by the number of articles that have been published on the subject. We conducted a systematic review of all studies that investigated GR gene methylation in relation to various psychological stressors, including parental stress; adverse early-life social environments in animals, such as interventions affecting early environment; ELA in humans; and psychological stress or psychopathology in adults.
      Most of these studies investigated the GR exon variant 1F, and studies considering early-life and in utero adversity mostly reported increased methylation at this exon. In particular, negative early-life social environments were associated with greater exon 1F methylation in the large majority of studies (70% of animal ELA studies and 90% of human ELA studies assessing exon 1F; 100% of parental stress studies assessing exon 1F). In studies of gestational stress, it is important to note that four studies collected tissue samples at birth (
      • Oberlander T.F.
      • Weinberg J.
      • Papsdorf M.
      • Grunau R.
      • Misri S.
      • Devlin A.M.
      Prenatal exposure to maternal depression, neonatal methylation of human glucocorticoid receptor gene (NR3C1) and infant cortisol stress responses.
      ,
      • Conradt E.
      • Lester B.M.
      • Appleton A.A.
      • Armstrong D.A.
      • Marsit C.J.
      The roles of DNA methylation of NR3C1 and 11beta-HSD2 and exposure to maternal mood disorder in utero on newborn neurobehavior.
      ,
      • Hompes T.
      • Izzi B.
      • Gellens E.
      • Morreels M.
      • Fieuws S.
      • Pexsters A.
      • et al.
      Investigating the influence of maternal cortisol and emotional state during pregnancy on the DNA methylation status of the glucocorticoid receptor gene (NR3C1) promoter region in cord blood.
      ,
      • Mulligan C.J.
      • D׳Errico N.C.
      • Stees J.
      • Hughes D.A.
      Methylation changes at NR3C1 in newborns associate with maternal prenatal stress exposure and newborn birth weight.
      ), and it is therefore unclear whether the observed changes would persist into adulthood. However, the other studies included used adolescent or adult subjects (
      • Essex M.J.
      • Boyce W.T.
      • Hertzman C.
      • Lam L.L.
      • Armstrong J.M.
      • Neumann S.M.
      • Kobor M.S.
      Epigenetic vestiges of early developmental adversity: Childhood stress exposure and DNA methylation in adolescence.
      ,
      • Radtke K.M.
      • Ruf M.
      • Gunter H.M.
      • Dohrmann K.
      • Schauer M.
      • Meyer A.
      • Elbert T.
      Transgenerational impact of intimate partner violence on methylation in the promoter of the glucocorticoid receptor.
      ,
      • Perroud N.
      • Rutembesa E.
      • Paoloni-Giacobino A.
      • Mutabaruka J.
      • Mutesa L.
      • Stenz L.
      • et al.
      The Tutsi genocide and transgenerational transmission of maternal stress: Epigenetics and biology of the HPA axis.
      ,
      • Yehuda R.
      • Daskalakis N.P.
      • Lehrner A.
      • Desarnaud F.
      • Bader H.N.
      • Makotkine I.
      • et al.
      Influences of maternal and paternal PTSD on epigenetic regulation of the glucocorticoid receptor gene in Holocaust survivor offspring.
      ). When combined with the ELA studies, these findings show a compelling consensus of increased exon 1F methylation in conjunction with stress in early life (16 of 17 studies; human studies from Tables S1 and S2, combined, that investigated exon 1F).
      The strength of the association between adverse postnatal social environments and GR1F methylation in humans is consistent with the original report from McGowan et al. (
      • McGowan P.O.
      • Sasaki A.
      • D׳Alessio A.C.
      • Dymov S.
      • Labonte B.
      • Szyf M.
      • et al.
      Epigenetic regulation of the glucocorticoid receptor in human brain associates with childhood abuse.
      ). Interindividual differences in DNA methylation can be tissue and cell type specific, yet we found multiple reports of associations between the quality of childhood experience and the methylation status of the exon 1F NR3C1 gene promoter in readily accessible peripheral cells. Perroud et al. (
      • Perroud N.
      • Dayer A.
      • Piguet C.
      • Nallet A.
      • Favre S.
      • Malafosse A.
      • Aubry J.M.
      Childhood maltreatment and methylation of the glucocorticoid receptor gene NR3C1 in bipolar disorder.
      ,
      • Perroud N.
      • Paoloni-Giacobino A.
      • Prada P.
      • Olie E.
      • Salzmann A.
      • Nicastro R.
      • et al.
      Increased methylation of glucocorticoid receptor gene (NR3C1) in adults with a history of childhood maltreatment: A link with the severity and type of trauma.
      ) used peripheral blood lymphocytes to show that childhood maltreatment associates with increased exon 1F methylation and, importantly, that promoter methylation status was closely correlated with both the frequency and severity of maltreatment [also see (
      • Romens S.E.
      • McDonald J.
      • Svaren J.
      • Pollak S.D.
      Associations between early life stress and gene methylation in children [published online ahead of print July 24].
      )]. Interestingly, Tyrka et al. (
      • Tyrka A.R.
      • Price L.H.
      • Marsit C.
      • Walters O.C.
      • Carpenter L.L.
      Childhood adversity and epigenetic modulation of the leukocyte glucocorticoid receptor: Preliminary findings in healthy adults.
      ) reported that increased methylation of the exon 1F NR3C1 gene promoter in leukocytes, associated with disruption of normal parent-offspring interactions or maltreatment, was linked to an attenuated cortisol response to the dexamethasone/CRH test. In this study and that of Melas et al. (
      • Melas P.A.
      • Wei Y.
      • Wong C.C.
      • Sjoholm L.K.
      • Aberg E.
      • Mill J.
      • et al.
      Genetic and epigenetic associations of MAOA and NR3C1 with depression and childhood adversities.
      ), childhood parental loss was associated with increased methylation of the exon 1F NR3C1 gene promoter [note the Melas et al. (
      • Melas P.A.
      • Wei Y.
      • Wong C.C.
      • Sjoholm L.K.
      • Aberg E.
      • Mill J.
      • et al.
      Genetic and epigenetic associations of MAOA and NR3C1 with depression and childhood adversities.
      ) study used salivary DNA, which is primarily of leukocyte origin (
      • Thiede C.
      • Prange-Krex G.
      • Freiberg-Richter J.
      • Bornhauser M.
      • Ehninger G.
      Buccal swabs but not mouthwash samples can be used to obtain pretransplant DNA fingerprints from recipients of allogeneic bone marrow transplants.
      )].
      These findings appear despite the significant evidence of tissue-specific DNA methylation profiles (
      • Davies M.N.
      • Volta M.
      • Pidsley R.
      • Lunnon K.
      • Dixit A.
      • Lovestone S.
      • et al.
      Functional annotation of the human brain methylome identifies tissue-specific epigenetic variation across brain and blood.
      ,
      • Liang P.
      • Song F.
      • Ghosh S.
      • Morien E.
      • Qin M.
      • Mahmood S.
      • et al.
      Genome-wide survey reveals dynamic widespread tissue-specific changes in DNA methylation during development.
      ,
      • Xin Y.
      • Chanrion B.
      • Liu M.M.
      • Galfalvy H.
      • Costa R.
      • Ilievski B.
      • et al.
      Genome-wide divergence of DNA methylation marks in cerebral and cerebellar cortices.
      ,
      • Xin Y.
      • O׳Donnell A.H.
      • Ge Y.
      • Chanrion B.
      • Milekic M.
      • Rosoklija G.
      • et al.
      Role of CpG context and content in evolutionary signatures of brain DNA methylation.
      ), leading to the question of how a social adversity-related epigenetic signal might appear in cell populations as diverse as peripheral blood cells and CNS-derived cells. One possibility is that social adversity activates stress responses that include signals such as steroid hormones (e.g., glucocorticoids) or cytokines, which act in multiple cell types and might initiate a coordinated remodeling of the epigenome at specific sites. While this reasoning is a matter of speculation, it does suggest a pathway by which the epigenetic imprint associated with social adversity might appear in a range of cell types, thus enabling meaningful population analyses of the effects of childhood environmental conditions on the epigenome. This also suggests that the nature of specific epigenetic marks across multiple tissues might be context specific: environmental conditions of sufficient biological impact, such as social adversity, might lead to coordinated changes that would enhance the probability of detecting specific epigenetic states across multiple tissues. This might also support the inclusion of epigenetic analyses of peripheral samples within intervention programs targeting brain-based phenotypes. The merits of this approach will become apparent with future studies focusing on a broader range of genomic targets, including genome-wide analyses [e.g., (
      • Essex M.J.
      • Boyce W.T.
      • Hertzman C.
      • Lam L.L.
      • Armstrong J.M.
      • Neumann S.M.
      • Kobor M.S.
      Epigenetic vestiges of early developmental adversity: Childhood stress exposure and DNA methylation in adolescence.
      )].
      The stability of DNA methylation is also a point of interest (
      • Ziller M.J.
      • Gu H.
      • Muller F.
      • Donaghey J.
      • Tsai L.T.
      • Kohlbacher O.
      • et al.
      Charting a dynamic DNA methylation landscape of the human genome.
      ). Recent evidence supports the hypothesis that epigenetic plasticity is sustained in the brain throughout adulthood, potentially as a mechanism to cope with the evolving demands of the environment; yet, there are clear moments during development when plasticity is heightened, and these may be more strongly associated with the establishment of life-long epigenetic modifications [reviewed in (
      • Auger C.J.
      • Auger A.P.
      Permanent and plastic epigenesis in neuroendocrine systems.
      )]. Another important consideration is that the studies cited here report low overall levels of methylation. This is consistent with the fact that strong CpG promoters, such as those from the GR gene, have generally low levels of methylation (
      • Weber M.
      • Hellmann I.
      • Stadler M.B.
      • Ramos L.
      • Paabo S.
      • Rebhan M.
      • Schübeler D.
      Distribution, silencing potential and evolutionary impact of promoter DNA methylation in the human genome.
      ).
      There has been great consistency regarding the increased methylation of the NGFI-A binding site within exon1F. There are also reports of differential methylation at other sites of the GR promoter that are not associated with NGFI-A binding (Tables S1–3). However, the functional implications of such differential methylation have not been empirically tested, and further investigation of these sites is warranted. Although NGFI-A is enriched in the brain, it appears to be expressed ubiquitously (
      • Watson M.A.
      • Milbrandt J.
      Expression of the nerve growth factor-regulated NGFI-A and NGFI-B genes in the developing rat.
      ) and belongs to the early growth response family of proteins, which contain a zinc-finger motif, allowing for interactions with target DNA regions (
      • O׳Donovan K.J.
      • Tourtellotte W.G.
      • Millbrandt J.
      • Baraban J.M.
      The EGR family of transcription-regulatory factors: Progress at the interface of molecular and systems neuroscience.
      ). NGFI-A is activated by a range of stimuli, including neurotransmitters and cellular stimulation, and is a key contributor to T lymphocyte proliferation (
      • Perez-Castillo A.
      • Pipaon C.
      • Garcia I.
      • Alemany S.
      NGFI-A gene expression is necessary for T lymphocyte proliferation.
      ). Therefore, blocking NGFI-A binding sites in the GR gene promoter in peripheral tissues (blood and saliva, in which the majority of DNA-contributing cells are lymphocytes) is likely to actively contribute to the regulation of GR expression.
      The activity of the HPA axis is governed by corticotropin-releasing factor and arginine vasopressin, both of which are subject to GR-mediated feedback regulation at multiple levels within the axis and inhibition from extra-hypothalamic sites. Hippocampal GR activation associates with the inhibition of hypothalamic CRF synthesis and dampened HPA activity (
      • Sapolsky R.M.
      • Romero L.M.
      • Munck A.U.
      How do glucocorticoids influence stress responses? Integrating permissive, suppressive, stimulatory, and preparative actions.
      ). Studies with adults reveal that childhood maltreatment is associated with an increased HPA response to stress (
      • Heim C.
      • Mletzko T.
      • Purselle D.
      • Musselman D.L.
      • Nemeroff C.B.
      The dexamethasone/corticotropin-releasing factor test in men with major depression: Role of childhood trauma.
      ,
      • Heim C.
      • Newport D.J.
      • Heit S.
      • Graham Y.P.
      • Wilcox M.
      • Bonsall R.
      • et al.
      Pituitary-adrenal and autonomic responses to stress in women after sexual and physical abuse in childhood.
      ). Subsequent statistical analyses revealed that childhood abuse was the strongest predictor of adrenocorticotropic hormone (ACTH) responsiveness, followed by the number of abuse events, adulthood traumas, and depression. An interaction term of childhood and adulthood trauma proved to be the most potent predictor of ACTH responses, suggesting that a history of childhood abuse per se is related to increased stress reactivity, which is further enhanced when additional trauma occurs in adulthood (
      • Heim C.
      • Mletzko T.
      • Purselle D.
      • Musselman D.L.
      • Nemeroff C.B.
      The dexamethasone/corticotropin-releasing factor test in men with major depression: Role of childhood trauma.
      ,
      • Heim C.
      • Newport D.J.
      • Wagner D.
      • Wilcox M.M.
      • Miller A.H.
      • Nemeroff C.B.
      The role of early adverse experience and adulthood stress in the prediction of neuroendocrine stress reactivity in women: A multiple regression analysis.
      ). Among women with no history of major depressive disorder, childhood trauma was similarly associated with and increased ACTH response to stress (
      • Heim C.
      • Mletzko T.
      • Purselle D.
      • Musselman D.L.
      • Nemeroff C.B.
      The dexamethasone/corticotropin-releasing factor test in men with major depression: Role of childhood trauma.
      ).
      There is evidence for elevated cerebrospinal fluid levels of CRF in adults associated with a history of childhood maltreatment (
      • Heim C.
      • Newport D.J.
      • Mletzko T.
      • Miller A.H.
      • Nemeroff C.B.
      The link between childhood trauma and depression: Insights from HPA axis studies in humans.
      ,
      • Lee R.
      • Geracioti Jr, T.D.
      • Kasckow J.W.
      • Coccaro E.F.
      Childhood trauma and personality disorder: Positive correlation with adult CSF corticotropin-releasing factor concentrations.
      ), poor quality of parental care (
      • Lee R.J.
      • Gollan J.
      • Kasckow J.
      • Geracioti T.
      • Coccaro E.F.
      CSF corticotropin-releasing factor in personality disorder: Relationship with self-reported parental care.
      ), and childhood stressful experience (
      • Carpenter L.L.
      • Tyrka A.R.
      • McDougle C.J.
      • Malison R.T.
      • Owens M.J.
      • Nemeroff C.B.
      • Price L.H.
      Cerebrospinal fluid corticotropin-releasing factor and perceived early-life stress in depressed patients and healthy control subjects.
      ). Heim et al. (
      • Heim C.
      • Newport D.J.
      • Mletzko T.
      • Miller A.H.
      • Nemeroff C.B.
      The link between childhood trauma and depression: Insights from HPA axis studies in humans.
      ) showed that cerebrospinal fluid CRF concentrations were correlated with the severity and duration of physical and sexual abuse, and high CRF may arise due to GR downregulation and impaired negative feedback inhibition, as supported by early reports linking childhood abuse with higher cortisol response to the dexamethasone/CRH challenge test in adults (
      • Heim C.
      • Mletzko T.
      • Purselle D.
      • Musselman D.L.
      • Nemeroff C.B.
      The dexamethasone/corticotropin-releasing factor test in men with major depression: Role of childhood trauma.
      ,
      • Rinne T.
      • de Kloet E.R.
      • Wouters L.
      • Goekoop J.G.
      • DeRijk R.H.
      • van den Brink W.
      Hyperresponsiveness of hypothalamic-pituitary-adrenal axis to combined dexamethasone/corticotropin-releasing hormone challenge in female borderline personality disorder subjects with a history of sustained childhood abuse.
      ). Recent work has shown that some subjects having experienced childhood abuse exhibit lower levels of cortisol, with marked differences depending on gender (
      • Power C.
      • Thomas C.
      • Li L.
      • Hertzman C.
      Childhood psychosocial adversity and adult cortisol patterns.
      ,
      • Elzinga B.M.
      • Roelofs K.
      • Tollenaar M.S.
      • Bakvis P.
      • van Pelt J.
      • Spinhoven P.
      Diminished cortisol responses to psychosocial stress associated with lifetime adverse events a study among healthy young subjects.
      ,
      • Seltzer L.J.
      • Ziegler T.
      • Connolly M.J.
      • Prososki A.R.
      • Pollak S.D.
      Stress-induced elevation of oxytocin in maltreated children: Evolution, neurodevelopment, and social behavior.
      ,
      • Doom J.R.
      • Cicchetti D.
      • Rogosch F.A.
      • Dackis M.N.
      Child maltreatment and gender interactions as predictors of differential neuroendocrine profiles.
      ), time of cortisol sampling (
      • Power C.
      • Thomas C.
      • Li L.
      • Hertzman C.
      Childhood psychosocial adversity and adult cortisol patterns.
      ), source tissue (
      • Steudte S.
      • Kirschbaum C.
      • Gao W.
      • Alexander N.
      • Schonfeld S.
      • Hoyer J.
      • Stalder T.
      Hair cortisol as a biomarker of traumatization in healthy individuals and posttraumatic stress disorder patients.
      ), type of abuse (
      • Bublitz M.H.
      • Parade S.
      • Stroud L.R.
      The effects of childhood sexual abuse on cortisol trajectories in pregnancy are moderated by current family functioning.
      ,
      • Bublitz M.H.
      • Stroud L.R.
      Childhood sexual abuse is associated with cortisol awakening response over pregnancy: Preliminary findings.
      ), and the presence of concurrent psychiatric (
      • Heim C.
      • Mletzko T.
      • Purselle D.
      • Musselman D.L.
      • Nemeroff C.B.
      The dexamethasone/corticotropin-releasing factor test in men with major depression: Role of childhood trauma.
      ,
      • Rinne T.
      • de Kloet E.R.
      • Wouters L.
      • Goekoop J.G.
      • DeRijk R.H.
      • van den Brink W.
      Hyperresponsiveness of hypothalamic-pituitary-adrenal axis to combined dexamethasone/corticotropin-releasing hormone challenge in female borderline personality disorder subjects with a history of sustained childhood abuse.
      ) or other health conditions (
      • Bublitz M.H.
      • Parade S.
      • Stroud L.R.
      The effects of childhood sexual abuse on cortisol trajectories in pregnancy are moderated by current family functioning.
      ). Importantly, decreased cortisol may not be exclusively linked to posttraumatic stress disorder (
      • Steudte S.
      • Kirschbaum C.
      • Gao W.
      • Alexander N.
      • Schonfeld S.
      • Hoyer J.
      • Stalder T.
      Hair cortisol as a biomarker of traumatization in healthy individuals and posttraumatic stress disorder patients.
      ,
      • Lovallo W.R.
      • Farag N.H.
      • Sorocco K.H.
      • Cohoon A.J.
      • Vincent A.S.
      Lifetime adversity leads to blunted stress axis reactivity: Studies from the Oklahoma Family Health Patterns Project.
      ), as has often been supposed (
      • Yehuda R.
      • Seckl J.
      Minireview: Stress-related psychiatric disorders with low cortisol levels: A metabolic hypothesis.
      ,
      • Ehlert U.
      Enduring psychobiological effects of childhood adversity.
      ); rather, decreased cortisol production may reflect an adaptation to chronically stressful situations, whereas elevated cortisol production may prime individuals to react to unpredictable stressors, and these situations may both constitute ELA (
      • Seltzer L.J.
      • Ziegler T.
      • Connolly M.J.
      • Prososki A.R.
      • Pollak S.D.
      Stress-induced elevation of oxytocin in maltreated children: Evolution, neurodevelopment, and social behavior.
      ). Currently, it is difficult to draw conclusions on the overall impact of GR methylation variations on basal and reactive cortisol levels, as the majority of studies investigating GR promoter methylation did not measure cortisol levels.
      These findings suggest that childhood adversity stably influences HPA responses to stress. Childhood adversity moderates the relation between stressful life events in adulthood and depression, with increased risk for depression or anxiety in response to moderately stressful circumstances among individuals with a history of childhood adversity (
      • McLaughlin K.A.
      • Green J.G.
      • Gruber M.J.
      • Sampson N.A.
      • Zaslavsky A.M.
      • Kessler R.C.
      Childhood adversities and adult psychiatric disorders in the national comorbidity survey replication II: Associations with persistence of DSM-IV disorders.
      ,
      • Widom C.S.
      • DuMont K.
      • Czaja S.J.
      A prospective investigation of major depressive disorder and comorbidity in abused and neglected children grown up.
      ,
      • Wichers M.
      • Geschwind N.
      • Jacobs N.
      • Kenis G.
      • Peeters F.
      • Derom C.
      • et al.
      Transition from stress sensitivity to a depressive state: Longitudinal twin study.
      ). This is consistent with the idea that childhood maltreatment sensitizes neural and endocrine responses to stress, thus establishing a vulnerability for mood disorders.
      Recent rodent studies suggest that epigenetic programming of HPA function occurs at multiple levels of the HPA axis in addition to effects on hippocampal GR expression. Environmental conditions that increase the frequency of LG in the rat are associated with decreased paraventricular CRF expression (
      • Liu D.
      • Diorio J.
      • Tannenbaum B.
      • Caldji C.
      • Francis D.
      • Freedman A.
      • et al.
      Maternal care, hippocampal glucocorticoid receptors, and hypothalamic-pituitary-adrenal responses to stress.
      ,
      • Plotsky P.M.
      • Meaney M.J.
      Early, postnatal experience alters hypothalamic corticotropin-releasing factor (CRF) mRNA, median eminence CRF content and stress-induced release in adult rats.
      ,
      • Fenoglio K.A.
      • Brunson K.L.
      • Avishai-Eliner S.
      • Stone B.A.
      • Kapadia B.J.
      • Baram T.Z.
      Enduring, handling-evoked enhancement of hippocampal memory function and glucocorticoid receptor expression involves activation of the corticotropin-releasing factor type 1 receptor.
      ,
      • Plotsky P.M.
      • Thrivikraman K.V.
      • Nemeroff C.B.
      • Caldji C.
      • Sharma S.
      • Meaney M.J.
      Long-term consequences of neonatal rearing on central corticotropin-releasing factor systems in adult male rat offspring.
      ). Avishai-Eliner et al. (
      • Avishai-Eliner S.
      • Gilles E.E.
      • Eghbal-Ahmadi M.
      • Bar-El Y.
      • Baram T.Z.
      Altered regulation of gene and protein expression of hypothalamic-pituitary-adrenal axis components in an immature rat model of chronic stress.
      ) showed that this maternally regulated decrease in CRF expression is accompanied by an increased hypothalamic expression of the transcriptional repressor neuron-restrictive silencer factor and neuron-restrictive silencer factor binding to a 21 base pair sequence within the regulatory region (intron) of the Crh gene (
      • Seth K.A.
      • Majzoub J.A.
      Repressor element silencing transcription factor/neuron-restrictive silencing factor (REST/NRSF) can act as an enhancer as well as a repressor of corticotropin-releasing hormone gene transcription.
      ). Korosi et al. (
      • Korosi A.
      • Shanabrough M.
      • McClelland S.
      • Liu Z.W.
      • Borok E.
      • Gao X.B.
      • et al.
      Early-life experience reduces excitation to stress-responsive hypothalamic neurons and reprograms the expression of corticotropin-releasing hormone.
      ) showed that augmented maternal care reduced the number of excitatory synapses onto CRF neurons. A study where CRF expression was increased through disruption of maternal care in the mouse (
      • Rice C.J.
      • Sandman C.A.
      • Lenjavi M.R.
      • Baram T.Z.
      A novel mouse model for acute and long-lasting consequences of early life stress.
      ) showed enhanced glutamatergic transmission to hypothalamic CRF neurons in the offspring (
      • Gunn B.G.
      • Cunningham L.
      • Cooper M.A.
      • Corteen N.L.
      • Seifi M.
      • Swinny J.D.
      • et al.
      Dysfunctional astrocytic and synaptic regulation of hypothalamic glutamatergic transmission in a mouse model of early-life adversity: Relevance to neurosteroids and programming of the stress response.
      ). Moreover, prolonged periods of maternal separation alter the methylation state of the promoter for the Avp gene, increasing hypothalamic arginine vasopressin synthesis and HPA responses to stress (
      • Murgatroyd C.
      • Patchev A.V.
      • Wu Y.
      • Micale V.
      • Bockmuhl Y.
      • Fischer D.
      • et al.
      Dynamic DNA methylation programs persistent adverse effects of early-life stress.
      ). Maternal separation of neonatal mice also produces an enduring hypomethylation of the Pomc gene, which encodes for the ACTH prohormone, pro-opiomelanocortin (
      • Wu Y.
      • Patchev A.V.
      • Daniel G.
      • Almeida O.F.
      • Spengler D.
      Early-life stress reduces DNA methylation of the Pomc gene in male mice.
      ), increased pro-opiomelanocortin messenger RNA expression, and increased basal and CRF-induced levels of ACTH. These findings extend previous studies of hippocampal GR regulation and reveal that the quality of postnatal maternal care in rodents epigenetically programs gene expression at multiple levels of the HPA axis to regulate both basal and stress-induced activity.
      The initial reports of epigenetic regulation of hippocampal GR expression are now accompanied by reports of environmentally regulated alterations in the methylation status of multiple genes directly implicated in HPA function. Likewise, in humans, childhood maltreatment associates with differential methylation of the FKBP5 gene, which encodes for a functional regulator of GR signaling. FKBP5 alters glucocorticoid receptor function by decreasing ligand binding and impeding translocation of the receptor complex to the nucleus. Childhood maltreatment produces an FKBP5 genotype-specific demethylation of a distal enhancer, resulting in increased FKBP5 expression and decreased GR signaling (
      • Klengel T.
      • Mehta D.
      • Anacker C.
      • Rex-Haffner M.
      • Pruessner J.C.
      • Pariante C.M.
      • et al.
      Allele-specific FKBP5 DNA demethylation mediates gene-childhood trauma interactions.
      ). A remarkable feature of these findings is the coordinated epigenetic effects on multiple genes, in multiple tissues, that collectively serve to increase HPA responsivity to stress in response to early social adversity.

      Acknowledgments And Disclosures

      GT is supported by the following grants from the Canadian Institute of Health Research : Grant Nos. MOP93775 , MOP11260 , MOP119429 , and MOP119430 ; from the National Institutes of Health , Grant No. 1R01DA033684-01 ; and by the Fonds de Recherche du Québec - Santé through a Chercheur National Salary Award and through the Quebec Network on Suicide, Mood Disorders, and Related Disorders.
      We thank Germaine Lowe, Dave Checknita, and Sylvanne Daniels for their invaluable help retrieving and processing original papers for this review.
      The authors report no biomedical financial interests or potential conflicts of interest.

      Appendix A. Supplementary Materials

      References

        • Evans E.
        • Hawton K.
        • Rodham K.
        Suicidal phenomena and abuse in adolescents: A review of epidemiological studies.
        Child Abuse Negl. 2005; 29: 45-58
        • Ystgaard M.
        • Hestetun I.
        • Loeb M.
        • Mehlum L.
        Is there a specific relationship between childhood sexual and physical abuse and repeated suicidal behavior?.
        Child Abuse Negl. 2004; 28: 863-875
        • Gilbert R.
        • Widom C.S.
        • Browne K.
        • Fergusson D.
        • Webb E.
        • Janson S.
        Burden and consequences of child maltreatment in high-income countries.
        Lancet. 2009; 373: 68-81
        • Collishaw S.
        • Pickles A.
        • Messer J.
        • Rutter M.
        • Shearer C.
        • Maughan B.
        Resilience to adult psychopathology following childhood maltreatment: Evidence from a community sample.
        Child Abuse Negl. 2007; 31: 211-229
        • McLaughlin K.A.
        • Green J.G.
        • Gruber M.J.
        • Sampson N.A.
        • Zaslavsky A.M.
        • Kessler R.C.
        Childhood adversities and adult psychiatric disorders in the national comorbidity survey replication II: Associations with persistence of DSM-IV disorders.
        Arch Gen Psychiatry. 2010; 67: 124-132
        • Edwards V.J.
        • Holden G.W.
        • Felitti V.J.
        • Anda R.F.
        Relationship between multiple forms of childhood maltreatment and adult mental health in community respondents: Results from the adverse childhood experiences study.
        Am J Psychiatry. 2003; 160: 1453-1460
        • Kessler R.C.
        • Davis C.G.
        • Kendler K.S.
        Childhood adversity and adult psychiatric disorder in the US National Comorbidity Survey.
        Psychol Med. 1997; 27: 1101-1119
        • Afifi T.O.
        • Enns M.W.
        • Cox B.J.
        • Asmundson G.J.
        • Stein M.B.
        • Sareen J.
        Population attributable fractions of psychiatric disorders and suicide ideation and attempts associated with adverse childhood experiences.
        Am J Public Health. 2008; 98: 946-952
        • Widom C.S.
        Posttraumatic stress disorder in abused and neglected children grown up.
        Am J Psychiatry. 1999; 156: 1223-1229
        • Widom C.S.
        • DuMont K.
        • Czaja S.J.
        A prospective investigation of major depressive disorder and comorbidity in abused and neglected children grown up.
        Arch Gen Psychiatry. 2007; 64: 49-56
        • Widom C.S.
        • White H.R.
        • Czaja S.J.
        • Marmorstein N.R.
        Long-term effects of child abuse and neglect on alcohol use and excessive drinking in middle adulthood.
        J Stud Alcohol Drugs. 2007; 68: 317-326
        • Lansford J.E.
        • Dodge K.A.
        • Pettit G.S.
        • Bates J.E.
        • Crozier J.
        • Kaplow J.
        A 12-year prospective study of the long-term effects of early child physical maltreatment on psychological, behavioral, and academic problems in adolescence.
        Arch Pediatr Adolesc Med. 2002; 156: 824-830
        • Meaney M.J.
        Maternal care, gene expression, and the transmission of individual differences in stress reactivity across generations.
        Annu Rev Neurosci. 2001; 24: 1161-1192
        • Levine A.
        • Cohen D.
        • Zadik Z.
        Urinary free cortisol values in children under stress.
        J Pediatr. 1994; 125: 853-857
        • Higley J.D.
        • Hasert M.F.
        • Suomi S.J.
        • Linnoila M.
        Nonhuman primate model of alcohol abuse: Effects of early experience, personality, and stress on alcohol consumption.
        Proc Natl Acad Sci U S A. 1991; 88: 7261-7265
        • Weaver I.C.
        • Cervoni N.
        • Champagne F.A.
        • D׳Alessio A.C.
        • Sharma S.
        • Seckl J.R.
        • et al.
        Epigenetic programming by maternal behavior.
        Nat Neurosci. 2004; 7: 847-854
        • Francis D.
        • Diorio J.
        • Liu D.
        • Meaney M.J.
        Nongenomic transmission across generations of maternal behavior and stress responses in the rat.
        Science. 1999; 286: 1155-1158
        • Liu D.
        • Diorio J.
        • Tannenbaum B.
        • Caldji C.
        • Francis D.
        • Freedman A.
        • et al.
        Maternal care, hippocampal glucocorticoid receptors, and hypothalamic-pituitary-adrenal responses to stress.
        Science. 1997; 277: 1659-1662
        • McGowan P.O.
        • Sasaki A.
        • D׳Alessio A.C.
        • Dymov S.
        • Labonte B.
        • Szyf M.
        • et al.
        Epigenetic regulation of the glucocorticoid receptor in human brain associates with childhood abuse.
        Nat Neurosci. 2009; 12: 342-348
        • Oberlander T.F.
        • Weinberg J.
        • Papsdorf M.
        • Grunau R.
        • Misri S.
        • Devlin A.M.
        Prenatal exposure to maternal depression, neonatal methylation of human glucocorticoid receptor gene (NR3C1) and infant cortisol stress responses.
        Epigenetics. 2008; 3: 97-106
        • Steiger H.
        • Labonte B.
        • Groleau P.
        • Turecki G.
        • Israel M.
        Methylation of the glucocorticoid receptor gene promoter in bulimic women: Associations with borderline personality disorder, suicidality, and exposure to childhood abuse.
        Int J Eat Disord. 2013; 46: 246-255
        • Desarnaud F.
        • Jakovcevski M.
        • Morellini F.
        • Schachner M.
        Stress downregulates hippocampal expression of the adhesion molecules NCAM and CHL1 in mice by mechanisms independent of DNA methylation of their promoters.
        Cell Adh Migr. 2008; 2: 38-44
        • Liberman S.A.
        • Mashoodh R.
        • Thompson R.C.
        • Dolinoy D.C.
        • Champagne F.A.
        Concordance in hippocampal and fecal Nr3c1 methylation is moderated by maternal behavior in the mouse.
        Ecol Evol. 2012; 2: 3123-3131
        • Witzmann S.R.
        • Turner J.D.
        • Meriaux S.B.
        • Meijer O.C.
        • Muller C.P.
        Epigenetic regulation of the glucocorticoid receptor promoter 1(7) in adult rats.
        Epigenetics. 2012; 7: 1290-1301
        • Melas P.A.
        • Wei Y.
        • Wong C.C.
        • Sjoholm L.K.
        • Aberg E.
        • Mill J.
        • et al.
        Genetic and epigenetic associations of MAOA and NR3C1 with depression and childhood adversities.
        Int J Neuropsychopharmacol. 2013; 16: 1513-1528
        • Weder N.
        • Zhang H.
        • Jensen K.
        • Yang B.Z.
        • Simen A.
        • Jackowski A.
        • et al.
        Child abuse, depression, and methylation in genes involved with stress, neural plasticity, and brain circuitry.
        J Am Acad Child Adolesc Psychiatry. 2014; 53: 417-424
        • Essex M.J.
        • Boyce W.T.
        • Hertzman C.
        • Lam L.L.
        • Armstrong J.M.
        • Neumann S.M.
        • Kobor M.S.
        Epigenetic vestiges of early developmental adversity: Childhood stress exposure and DNA methylation in adolescence.
        Child Dev. 2013; 84: 58-75
        • Conradt E.
        • Lester B.M.
        • Appleton A.A.
        • Armstrong D.A.
        • Marsit C.J.
        The roles of DNA methylation of NR3C1 and 11beta-HSD2 and exposure to maternal mood disorder in utero on newborn neurobehavior.
        Epigenetics. 2013; 8: 1321-1329
        • Labonte B.
        • Yerko V.
        • Gross J.
        • Mechawar N.
        • Meaney M.J.
        • Szyf M.
        • Turecki G.
        Differential glucocorticoid receptor exon 1(B), 1(C), and 1(H) expression and methylation in suicide completers with a history of childhood abuse.
        Biol Psychiatry. 2012; 72: 41-48
        • Alt S.R.
        • Turner J.D.
        • Klok M.D.
        • Meijer O.C.
        • Lakke E.A.
        • Derijk R.H.
        • Muller C.P.
        Differential expression of glucocorticoid receptor transcripts in major depressive disorder is not epigenetically programmed.
        Psychoneuroendocrinology. 2010; 35: 544-556
        • McCormick J.A.
        • Lyons V.
        • Jacobson M.D.
        • Noble J.
        • Diorio J.
        • Nyirenda M.
        • et al.
        5׳-heterogeneity of glucocorticoid receptor messenger RNA is tissue specific: Differential regulation of variant transcripts by early-life events.
        Mol Endocrinol. 2000; 14: 506-517
        • Weaver I.C.
        • Champagne F.A.
        • Brown S.E.
        • Dymov S.
        • Sharma S.
        • Meaney M.J.
        • Szyf M.
        Reversal of maternal programming of stress responses in adult offspring through methyl supplementation: Altering epigenetic marking later in life.
        J Neurosci. 2005; 25: 11045-11054
        • Henningsen K.
        • Dyrvig M.
        • Bouzinova E.V.
        • Christiansen S.
        • Christensen T.
        • Andreasen J.T.
        • et al.
        Low maternal care exacerbates adult stress susceptibility in the chronic mild stress rat model of depression.
        Behav Pharmacol. 2012; 23: 735-743
        • Kosten T.A.
        • Huang W.
        • Nielsen D.A.
        Sex and litter effects on anxiety and DNA methylation levels of stress and neurotrophin genes in adolescent rats.
        Dev Psychobiol. 2014; 56: 392-406
        • Kosten T.A.
        • Nielsen D.A.
        Litter and sex effects on maternal behavior and DNA methylation of the Nr3c1 exon 1 promoter gene in hippocampus and cerebellum.
        Int J Dev Neurosci. 2014; 36C: 5-12
        • Daniels W.M.
        • Fairbairn L.R.
        • van Tilburg G.
        • McEvoy C.R.
        • Zigmond M.J.
        • Russell V.A.
        • Stein D.J.
        Maternal separation alters nerve growth factor and corticosterone levels but not the DNA methylation status of the exon 1(7) glucocorticoid receptor promoter region.
        Metab Brain Dis. 2009; 24: 615-627
        • Kember R.L.
        • Dempster E.L.
        • Lee T.H.
        • Schalkwyk L.C.
        • Mill J.
        • Fernandes C.
        Maternal separation is associated with strain-specific responses to stress and epigenetic alterations to Nr3c1, Avp, and Nr4a1 in mouse.
        Brain Behav. 2012; 2: 455-467
        • Kundakovic M.
        • Lim S.
        • Gudsnuk K.
        • Champagne F.A.
        Sex-specific and strain-dependent effects of early life adversity on behavioral and epigenetic outcomes.
        Front Psychiatry. 2013; 4: 78
        • Tyrka A.R.
        • Price L.H.
        • Marsit C.
        • Walters O.C.
        • Carpenter L.L.
        Childhood adversity and epigenetic modulation of the leukocyte glucocorticoid receptor: Preliminary findings in healthy adults.
        PloS One. 2012; 7: e30148
        • van der Knaap L.J.
        • Riese H.
        • Hudziak J.J.
        • Verbiest M.M.
        • Verhulst F.C.
        • Oldehinkel A.J.
        • van Oort F.V.
        Glucocorticoid receptor gene (NR3C1) methylation following stressful events between birth and adolescence. The TRAILS study.
        Transl Psychiatry. 2014; 4: e381
        • Weaver I.C.
        • D׳Alessio A.C.
        • Brown S.E.
        • Hellstrom I.C.
        • Dymov S.
        • Sharma S.
        • et al.
        The transcription factor nerve growth factor-inducible protein a mediates epigenetic programming: Altering epigenetic marks by immediate-early genes.
        J Neurosci. 2007; 27: 1756-1768
        • Romens S.E.
        • McDonald J.
        • Svaren J.
        • Pollak S.D.
        Associations between early life stress and gene methylation in children [published online ahead of print July 24].
        Child Dev. 2014;
        • Guillemin C.
        • Provencal N.
        • Suderman M.
        • Cote S.M.
        • Vitaro F.
        • Hallett M.
        • et al.
        DNA methylation signature of childhood chronic physical aggression in T cells of both men and women.
        PloS One. 2014; 9: e86822
        • Mueller B.R.
        • Bale T.L.
        Sex-specific programming of offspring emotionality after stress early in pregnancy.
        J Neurosci. 2008; 28: 9055-9065
        • Hompes T.
        • Izzi B.
        • Gellens E.
        • Morreels M.
        • Fieuws S.
        • Pexsters A.
        • et al.
        Investigating the influence of maternal cortisol and emotional state during pregnancy on the DNA methylation status of the glucocorticoid receptor gene (NR3C1) promoter region in cord blood.
        J Psychiatr Res. 2013; 47: 880-891
        • Radtke K.M.
        • Ruf M.
        • Gunter H.M.
        • Dohrmann K.
        • Schauer M.
        • Meyer A.
        • Elbert T.
        Transgenerational impact of intimate partner violence on methylation in the promoter of the glucocorticoid receptor.
        Transl Psychiatry. 2011; 1: e21
        • Mulligan C.J.
        • D׳Errico N.C.
        • Stees J.
        • Hughes D.A.
        Methylation changes at NR3C1 in newborns associate with maternal prenatal stress exposure and newborn birth weight.
        Epigenetics. 2012; 7: 853-857
        • Perroud N.
        • Rutembesa E.
        • Paoloni-Giacobino A.
        • Mutabaruka J.
        • Mutesa L.
        • Stenz L.
        • et al.
        The Tutsi genocide and transgenerational transmission of maternal stress: Epigenetics and biology of the HPA axis.
        World J Biol Psychiatry. 2014; 15: 334-345
        • Yehuda R.
        • Daskalakis N.P.
        • Lehrner A.
        • Desarnaud F.
        • Bader H.N.
        • Makotkine I.
        • et al.
        Influences of maternal and paternal PTSD on epigenetic regulation of the glucocorticoid receptor gene in Holocaust survivor offspring.
        Am J Psychiatry. 2014; 171: 872-880
        • Tran L.
        • Chaloner A.
        • Sawalha A.H.
        • Greenwood Van-Meerveld B.
        Importance of epigenetic mechanisms in visceral pain induced by chronic water avoidance stress.
        Psychoneuroendocrinology. 2013; 38: 898-906
        • de Rooij S.R.
        • Costello P.M.
        • Veenendaal M.V.
        • Lillycrop K.A.
        • Gluckman P.D.
        • Hanson M.A.
        • et al.
        Associations between DNA methylation of a glucocorticoid receptor promoter and acute stress responses in a large healthy adult population are largely explained by lifestyle and educational differences.
        Psychoneuroendocrinology. 2012; 37: 782-788
        • Dammann G.
        • Teschler S.
        • Haag T.
        • Altmuller F.
        • Tuczek F.
        • Dammann R.H.
        Increased DNA methylation of neuropsychiatric genes occurs in borderline personality disorder.
        Epigenetics. 2011; 6: 1454-1462
        • Yehuda R.
        • Daskalakis N.P.
        • Desarnaud F.
        • Makotkine I.
        • Lehrner A.L.
        • Koch E.
        • et al.
        Epigenetic biomarkers as predictors and correlates of symptom improvement following psychotherapy in combat veterans with PTSD.
        Front Psychiatry. 2013; 4: 118
        • Yehuda R.
        • Flory J.D.
        • Bierer L.M.
        • Henn-Haase C.
        • Lehrner A.
        • Desarnaud F.
        • et al.
        Lower methylation of glucocorticoid receptor gene promoter 1 in peripheral blood of veterans with posttraumatic stress disorder.
        Biol Psychiatry. 2015; 77: 356-364
        • Labonte B.
        • Azoulay N.
        • Yerko V.
        • Turecki G.
        • Brunet A.
        Epigenetic modulation of glucocorticoid receptors in posttraumatic stress disorder.
        Transl Psychiatry. 2014; 4: e368
        • Na K.S.
        • Chang H.S.
        • Won E.
        • Han K.M.
        • Choi S.
        • Tae W.S.
        • et al.
        Association between glucocorticoid receptor methylation and hippocampal subfields in major depressive disorder.
        PloS One. 2014; 9: e85425
        • Perroud N.
        • Dayer A.
        • Piguet C.
        • Nallet A.
        • Favre S.
        • Malafosse A.
        • Aubry J.M.
        Childhood maltreatment and methylation of the glucocorticoid receptor gene NR3C1 in bipolar disorder.
        Br J Psychiatry. 2014; 204: 30-35
        • Perroud N.
        • Paoloni-Giacobino A.
        • Prada P.
        • Olie E.
        • Salzmann A.
        • Nicastro R.
        • et al.
        Increased methylation of glucocorticoid receptor gene (NR3C1) in adults with a history of childhood maltreatment: A link with the severity and type of trauma.
        Transl Psychiatry. 2011; 1: e59
        • Thiede C.
        • Prange-Krex G.
        • Freiberg-Richter J.
        • Bornhauser M.
        • Ehninger G.
        Buccal swabs but not mouthwash samples can be used to obtain pretransplant DNA fingerprints from recipients of allogeneic bone marrow transplants.
        Bone Marrow Transplant. 2000; 25: 575-577
        • Davies M.N.
        • Volta M.
        • Pidsley R.
        • Lunnon K.
        • Dixit A.
        • Lovestone S.
        • et al.
        Functional annotation of the human brain methylome identifies tissue-specific epigenetic variation across brain and blood.
        Genome Biol. 2012; 13: R43
        • Liang P.
        • Song F.
        • Ghosh S.
        • Morien E.
        • Qin M.
        • Mahmood S.
        • et al.
        Genome-wide survey reveals dynamic widespread tissue-specific changes in DNA methylation during development.
        BMC Genomics. 2011; 12: 231
        • Xin Y.
        • Chanrion B.
        • Liu M.M.
        • Galfalvy H.
        • Costa R.
        • Ilievski B.
        • et al.
        Genome-wide divergence of DNA methylation marks in cerebral and cerebellar cortices.
        PloS One. 2010; 5: e11357
        • Xin Y.
        • O׳Donnell A.H.
        • Ge Y.
        • Chanrion B.
        • Milekic M.
        • Rosoklija G.
        • et al.
        Role of CpG context and content in evolutionary signatures of brain DNA methylation.
        Epigenetics. 2011; 6: 1308-1318
        • Ziller M.J.
        • Gu H.
        • Muller F.
        • Donaghey J.
        • Tsai L.T.
        • Kohlbacher O.
        • et al.
        Charting a dynamic DNA methylation landscape of the human genome.
        Nature. 2013; 500: 477-481
        • Auger C.J.
        • Auger A.P.
        Permanent and plastic epigenesis in neuroendocrine systems.
        Front Neuroendocrinol. 2013; 34: 190-197
        • Weber M.
        • Hellmann I.
        • Stadler M.B.
        • Ramos L.
        • Paabo S.
        • Rebhan M.
        • Schübeler D.
        Distribution, silencing potential and evolutionary impact of promoter DNA methylation in the human genome.
        Nat Genet. 2007; 39: 457-466
        • Watson M.A.
        • Milbrandt J.
        Expression of the nerve growth factor-regulated NGFI-A and NGFI-B genes in the developing rat.
        Development. 1990; 110: 173-183
        • O׳Donovan K.J.
        • Tourtellotte W.G.
        • Millbrandt J.
        • Baraban J.M.
        The EGR family of transcription-regulatory factors: Progress at the interface of molecular and systems neuroscience.
        Trends Neurosci. 1999; 22: 167-173
        • Perez-Castillo A.
        • Pipaon C.
        • Garcia I.
        • Alemany S.
        NGFI-A gene expression is necessary for T lymphocyte proliferation.
        J Biol Chem. 1993; 268: 19445-19450
        • Sapolsky R.M.
        • Romero L.M.
        • Munck A.U.
        How do glucocorticoids influence stress responses? Integrating permissive, suppressive, stimulatory, and preparative actions.
        Endocr Rev. 2000; 21: 55-89
        • Heim C.
        • Mletzko T.
        • Purselle D.
        • Musselman D.L.
        • Nemeroff C.B.
        The dexamethasone/corticotropin-releasing factor test in men with major depression: Role of childhood trauma.
        Biol Psychiatry. 2008; 63: 398-405
        • Heim C.
        • Newport D.J.
        • Heit S.
        • Graham Y.P.
        • Wilcox M.
        • Bonsall R.
        • et al.
        Pituitary-adrenal and autonomic responses to stress in women after sexual and physical abuse in childhood.
        JAMA. 2000; 284: 592-597
        • Heim C.
        • Newport D.J.
        • Wagner D.
        • Wilcox M.M.
        • Miller A.H.
        • Nemeroff C.B.
        The role of early adverse experience and adulthood stress in the prediction of neuroendocrine stress reactivity in women: A multiple regression analysis.
        Depress Anxiety. 2002; 15: 117-125
        • Heim C.
        • Newport D.J.
        • Mletzko T.
        • Miller A.H.
        • Nemeroff C.B.
        The link between childhood trauma and depression: Insights from HPA axis studies in humans.
        Psychoneuroendocrinology. 2008; 33: 693-710
        • Lee R.
        • Geracioti Jr, T.D.
        • Kasckow J.W.
        • Coccaro E.F.
        Childhood trauma and personality disorder: Positive correlation with adult CSF corticotropin-releasing factor concentrations.
        Am J Psychiatry. 2005; 162: 995-997
        • Lee R.J.
        • Gollan J.
        • Kasckow J.
        • Geracioti T.
        • Coccaro E.F.
        CSF corticotropin-releasing factor in personality disorder: Relationship with self-reported parental care.
        Neuropsychopharmacology. 2006; 31: 2289-2295
        • Carpenter L.L.
        • Tyrka A.R.
        • McDougle C.J.
        • Malison R.T.
        • Owens M.J.
        • Nemeroff C.B.
        • Price L.H.
        Cerebrospinal fluid corticotropin-releasing factor and perceived early-life stress in depressed patients and healthy control subjects.
        Neuropsychopharmacology. 2004; 29: 777-784
        • Rinne T.
        • de Kloet E.R.
        • Wouters L.
        • Goekoop J.G.
        • DeRijk R.H.
        • van den Brink W.
        Hyperresponsiveness of hypothalamic-pituitary-adrenal axis to combined dexamethasone/corticotropin-releasing hormone challenge in female borderline personality disorder subjects with a history of sustained childhood abuse.
        Biol Psychiatry. 2002; 52: 1102-1112
        • Power C.
        • Thomas C.
        • Li L.
        • Hertzman C.
        Childhood psychosocial adversity and adult cortisol patterns.
        Br J Psychiatry. 2012; 201: 199-206
        • Elzinga B.M.
        • Roelofs K.
        • Tollenaar M.S.
        • Bakvis P.
        • van Pelt J.
        • Spinhoven P.
        Diminished cortisol responses to psychosocial stress associated with lifetime adverse events a study among healthy young subjects.
        Psychoneuroendocrinology. 2008; 33: 227-237
        • Seltzer L.J.
        • Ziegler T.
        • Connolly M.J.
        • Prososki A.R.
        • Pollak S.D.
        Stress-induced elevation of oxytocin in maltreated children: Evolution, neurodevelopment, and social behavior.
        Child Dev. 2014; 85: 501-512
        • Doom J.R.
        • Cicchetti D.
        • Rogosch F.A.
        • Dackis M.N.
        Child maltreatment and gender interactions as predictors of differential neuroendocrine profiles.
        Psychoneuroendocrinology. 2013; 38: 1442-1454
        • Steudte S.
        • Kirschbaum C.
        • Gao W.
        • Alexander N.
        • Schonfeld S.
        • Hoyer J.
        • Stalder T.
        Hair cortisol as a biomarker of traumatization in healthy individuals and posttraumatic stress disorder patients.
        Biol Psychiatry. 2013; 74: 639-646
        • Bublitz M.H.
        • Parade S.
        • Stroud L.R.
        The effects of childhood sexual abuse on cortisol trajectories in pregnancy are moderated by current family functioning.
        Biol Psychol. 2014; 103C: 152-157
        • Bublitz M.H.
        • Stroud L.R.
        Childhood sexual abuse is associated with cortisol awakening response over pregnancy: Preliminary findings.
        Psychoneuroendocrinology. 2012; 37: 1425-1430
        • Lovallo W.R.
        • Farag N.H.
        • Sorocco K.H.
        • Cohoon A.J.
        • Vincent A.S.
        Lifetime adversity leads to blunted stress axis reactivity: Studies from the Oklahoma Family Health Patterns Project.
        Biol Psychiatry. 2012; 71: 344-349
        • Yehuda R.
        • Seckl J.
        Minireview: Stress-related psychiatric disorders with low cortisol levels: A metabolic hypothesis.
        Endocrinology. 2011; 152: 4496-4503
        • Ehlert U.
        Enduring psychobiological effects of childhood adversity.
        Psychoneuroendocrinology. 2013; 38: 1850-1857
        • Wichers M.
        • Geschwind N.
        • Jacobs N.
        • Kenis G.
        • Peeters F.
        • Derom C.
        • et al.
        Transition from stress sensitivity to a depressive state: Longitudinal twin study.
        Br J Psychiatry. 2009; 195: 498-503
        • Plotsky P.M.
        • Meaney M.J.
        Early, postnatal experience alters hypothalamic corticotropin-releasing factor (CRF) mRNA, median eminence CRF content and stress-induced release in adult rats.
        Brain Res Mol Brain Res. 1993; 18: 195-200
        • Fenoglio K.A.
        • Brunson K.L.
        • Avishai-Eliner S.
        • Stone B.A.
        • Kapadia B.J.
        • Baram T.Z.
        Enduring, handling-evoked enhancement of hippocampal memory function and glucocorticoid receptor expression involves activation of the corticotropin-releasing factor type 1 receptor.
        Endocrinology. 2005; 146: 4090-4096
        • Plotsky P.M.
        • Thrivikraman K.V.
        • Nemeroff C.B.
        • Caldji C.
        • Sharma S.
        • Meaney M.J.
        Long-term consequences of neonatal rearing on central corticotropin-releasing factor systems in adult male rat offspring.
        Neuropsychopharmacology. 2005; 30: 2192-2204
        • Avishai-Eliner S.
        • Gilles E.E.
        • Eghbal-Ahmadi M.
        • Bar-El Y.
        • Baram T.Z.
        Altered regulation of gene and protein expression of hypothalamic-pituitary-adrenal axis components in an immature rat model of chronic stress.
        J Neuroendocrinol. 2001; 13: 799-807
        • Seth K.A.
        • Majzoub J.A.
        Repressor element silencing transcription factor/neuron-restrictive silencing factor (REST/NRSF) can act as an enhancer as well as a repressor of corticotropin-releasing hormone gene transcription.
        J Biol Chem. 2001; 276: 13917-13923
        • Korosi A.
        • Shanabrough M.
        • McClelland S.
        • Liu Z.W.
        • Borok E.
        • Gao X.B.
        • et al.
        Early-life experience reduces excitation to stress-responsive hypothalamic neurons and reprograms the expression of corticotropin-releasing hormone.
        J Neurosci. 2010; 30: 703-713
        • Rice C.J.
        • Sandman C.A.
        • Lenjavi M.R.
        • Baram T.Z.
        A novel mouse model for acute and long-lasting consequences of early life stress.
        Endocrinology. 2008; 149: 4892-4900
        • Gunn B.G.
        • Cunningham L.
        • Cooper M.A.
        • Corteen N.L.
        • Seifi M.
        • Swinny J.D.
        • et al.
        Dysfunctional astrocytic and synaptic regulation of hypothalamic glutamatergic transmission in a mouse model of early-life adversity: Relevance to neurosteroids and programming of the stress response.
        J Neurosci. 2013; 33: 19534-19554
        • Murgatroyd C.
        • Patchev A.V.
        • Wu Y.
        • Micale V.
        • Bockmuhl Y.
        • Fischer D.
        • et al.
        Dynamic DNA methylation programs persistent adverse effects of early-life stress.
        Nat Neurosci. 2009; 12: 1559-1566
        • Wu Y.
        • Patchev A.V.
        • Daniel G.
        • Almeida O.F.
        • Spengler D.
        Early-life stress reduces DNA methylation of the Pomc gene in male mice.
        Endocrinology. 2014; 155: 1751-1762
        • Klengel T.
        • Mehta D.
        • Anacker C.
        • Rex-Haffner M.
        • Pruessner J.C.
        • Pariante C.M.
        • et al.
        Allele-specific FKBP5 DNA demethylation mediates gene-childhood trauma interactions.
        Nat Neurosci. 2013; 16: 33-41