Increased Number and Activity of a Lateral Subpopulation of Hypothalamic Orexin/Hypocretin Neurons Underlies the Expression of an Addicted State in Rats



      The orexin (hypocretin) system is important for reward-driven motivation but has not been implicated in the expression of a multiphenotype addicted state.


      Rats were assessed for economic demand for cocaine before and after 14 days of short access, long access, or intermittent access (IntA) to cocaine. Rats were also assessed for a number of other DSM-5–relevant addiction criteria following differential access conditions. Orexin system function was assessed by quantification of numbers and activity of orexin cells, pharmacological blockade of the orexin-1 receptor, and subregion-specific knockdown of orexin cell populations.


      IntA produced a cluster of addiction-like behaviors that closely recapitulate key diagnostic criteria for addiction to a greater extent than long access or short access. IntA was accompanied by an increase in number and activity of orexin-expressing neurons within the lateral hypothalamic subregion. This increase in orexin cell number and activity persisted during protracted withdrawal from cocaine for at least 150 days and was accompanied by enhanced incubation of craving in the same rats. Selective knockdown of lateral hypothalamic orexin neurons reduced motivation for cocaine, and orexin-1 receptor signaling played a larger role in drug seeking after IntA.


      We provide the first evidence that lateral hypothalamic orexin system function extends beyond general reward seeking to play a critical role in expression of a multiphenotype addiction-like state. Thus, the orexin system is a potential novel target for pharmacotherapies designed to treat cocaine addiction. In addition, these data point to the IntA model as a preferred approach to modeling addiction-like behavior in rats.


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        • James M.H.
        • Mahler S.V.
        • Moorman D.E.
        • Aston-Jones G.
        A decade of orexin/hypocretin and addiction: Where are we now?.
        Curr Top Behav Neurosci. 2017; 33: 247-281
        • Walker L.C.
        • Lawrence A.J.
        The role of orexins/hypocretins in alcohol use and abuse.
        Curr Top Behav Neurosci. 2017; 33: 221-246
        • DiLeone R.J.
        • Georgescu D.
        • Nestler E.J.
        Lateral hypothalamic neuropeptides in reward and drug addiction.
        Life Sci. 2003; 73: 759-768
        • Harris G.C.
        • Wimmer M.
        • Aston-Jones G.
        A role for lateral hypothalamic orexin neurons in reward seeking.
        Nature. 2005; 437: 556-559
        • Georgescu D.
        • Zachariou V.
        • Barrot M.
        • Mieda M.
        • Willie J.T.
        • Eisch A.J.
        • et al.
        Involvement of the lateral hypothalamic peptide orexin in morphine dependence and withdrawal.
        J Neurosci. 2003; 23: 3106-3111
        • Mahler S.V.
        • Moorman D.E.
        • Smith R.J.
        • James M.H.
        • Aston-Jones G.
        Motivational activation: A unifying hypothesis of orexin/hypocretin function.
        Nat Neurosci. 2014; 17: 1298-1303
        • Schmeichel B.E.
        • Matzeu A.
        • Koebel P.
        • Vendruscolo L.F.
        • Sidhu H.
        • Shahryari R.
        • et al.
        Knockdown of hypocretin attenuates extended access of cocaine self-administration in rats.
        Neuropsychopharmacology. 2018; 43: 2373-2382
        • de Lecea L.
        • Kilduff T.S.
        • Peyron C.
        • Gao X.
        • Foye P.E.
        • Danielson P.E.
        • et al.
        The hypocretins: Hypothalamus-specific peptides with neuroexcitatory activity.
        Proc Natl Acad Sci U S A. 1998; 95: 322-327
        • Sakurai T.
        • Amemiya A.
        • Ishii M.
        • Matsuzaki I.
        • Chemelli R.M.
        • Tanaka H.
        • et al.
        Orexins and orexin receptors: A family of hypothalamic neuropeptides and G protein-coupled receptors that regulate feeding behavior.
        Cell. 1998; 92: 573-585
        • Sartor G.C.
        • Aston-Jones G.S.
        A septal-hypothalamic pathway drives orexin neurons, which is necessary for conditioned cocaine preference.
        J Neurosci. 2012; 32: 4623-4631
        • Richardson K.A.
        • Aston-Jones G.
        Lateral hypothalamic orexin/hypocretin neurons that project to ventral tegmental area are differentially activated with morphine preference.
        J Neurosci. 2012; 32: 3809-3817
        • Lasheras M.C.
        • Laorden M.L.
        • Milanes M.V.
        • Nunez C.
        Corticotropin-releasing factor 1 receptor mediates the activity of the reward system evoked by morphine-induced conditioned place preference.
        Neuropharmacology. 2015; 95: 168-180
        • Estabrooke I.V.
        • McCarthy M.T.
        • Ko E.
        • Chou T.C.
        • Chemelli R.M.
        • Yanagisawa M.
        • et al.
        Fos expression in orexin neurons varies with behavioral state.
        J Neurosci. 2001; 21: 1656-1662
        • Murphy J.A.
        • Deurveilher S.
        • Semba K.
        Stimulant doses of caffeine induce c-FOS activation in orexin/hypocretin-containing neurons in rat.
        Neuroscience. 2003; 121: 269-275
        • Harris G.C.
        • Aston-Jones G.
        Arousal and reward: A dichotomy in orexin function.
        Trends Neurosci. 2006; 29: 571-577
        • Borgland S.L.
        • Taha S.A.
        • Sarti F.
        • Fields H.L.
        • Bonci A.
        Orexin A in the VTA is critical for the induction of synaptic plasticity and behavioral sensitization to cocaine.
        Neuron. 2006; 49: 589-601
        • Zhang G.C.
        • Mao L.M.
        • Liu X.Y.
        • Wang J.Q.
        Long-lasting up-regulation of orexin receptor type 2 protein levels in the rat nucleus accumbens after chronic cocaine administration.
        J Neurochem. 2007; 103: 400-407
        • Lawrence A.J.
        • Cowen M.S.
        • Yang H.J.
        • Chen F.
        • Oldfield B.
        The orexin system regulates alcohol-seeking in rats.
        Br J Pharmacol. 2006; 148: 752-759
        • James M.H.
        • Aston-Jones G.
        Orexin/hypocretin, central amygdala, and escalation of cocaine intake.
        Biol Psychiatry. 2017; 81: 552-553
        • Ahmed S.H.
        The science of making drug-addicted animals.
        Neuroscience. 2012; 211: 107-125
        • Ahmed S.H.
        • Koob G.F.
        Transition from moderate to excessive drug intake: Change in hedonic set point.
        Science. 1998; 282: 298-300
        • Allain F.
        • Minogianis E.A.
        • Roberts D.C.
        • Samaha A.N.
        How fast and how often: The pharmacokinetics of drug use are decisive in addiction.
        Neurosci Biobehav Rev. 2015; 56: 166-179
      1. Beveridge TJR, Wray P, Brewer A, Shapiro B, Mahoney JJ, Newton TF, et al. (2012): Analyzing human cocaine use patterns to inform animal addiction model development. Published abstract from College on Problems of Drug Dependence Annual Meeting, June 9–14, Palm Springs, California.

        • Zimmer B.A.
        • Oleson E.B.
        • Roberts D.C.S.
        The motivation to self-administer is increased after a history of spiking brain levels of cocaine.
        Neuropsychopharmacology. 2012; 37: 1901-1910
        • Calipari E.S.
        • Siciliano C.A.
        • Zimmer B.A.
        • Jones S.R.
        Brief intermittent cocaine self-administration and abstinence sensitizes cocaine effects on the dopamine transporter and increases drug seeking.
        Neuropsychopharmacology. 2015; 40: 728-735
        • Calipari E.S.
        • Ferris M.J.
        • Zimmer B.A.
        • Roberts D.C.
        • Jones S.R.
        Temporal pattern of cocaine intake determines tolerance vs sensitization of cocaine effects at the dopamine transporter.
        Neuropsychopharmacology. 2013; 38: 2385-2392
        • Kawa A.B.
        • Bentzley B.S.
        • Robinson T.E.
        Less is more: Prolonged intermittent access cocaine self-administration produces incentive-sensitization and addiction-like behavior.
        Psychopharmacology. 2016; 233: 3587-3602
        • Allain F.
        • Bouayad-Gervais K.
        • Samaha A.N.
        High and escalating levels of cocaine intake are dissociable from subsequent incentive motivation for the drug in rats.
        Psychopharmacology. 2018; 235: 317-328
        • Singer B.F.
        • Fadanelli M.
        • Kawa A.B.
        • Robinson T.E.
        Are cocaine-seeking “habits” necessary for the development of addiction-like behavior in rats?.
        J Neurosci. 2018; 38: 60-73
        • Bentzley B.S.
        • Fender K.M.
        • Aston-Jones G.
        The behavioral economics of drug self-administration: A review and new analytical approach for within-session procedures.
        Psychopharmacology. 2013; 226: 113-125
        • Oleson E.B.
        • Richardson J.M.
        • Roberts D.C.
        A novel IV cocaine self-administration procedure in rats: Differential effects of dopamine, serotonin, and GABA drug pre-treatments on cocaine consumption and maximal price paid.
        Psychopharmacology. 2011; 214: 567-577
        • Bentzley B.S.
        • Aston-Jones G.
        Orexin-1 receptor signaling increases motivation for cocaine-associated cues.
        Eur J Neurosci. 2015; 41: 1149-1156
        • Bentzley B.S.
        • Jhou T.C.
        • Aston-Jones G.
        Economic demand predicts addiction-like behavior and therapeutic efficacy of oxytocin in the rat.
        Proc Natl Acad Sci U S A. 2014; 111: 11822-11827
        • Hursh S.R.
        • Silberberg A.
        Economic demand and essential value.
        Psychol Rev. 2008; 115: 186-198
        • Reissner K.J.
        • Sartor G.C.
        • Vazey E.M.
        • Dunn T.E.
        • Aston-Jones G.
        • Kalivas P.W.
        Use of vivo-morpholinos for control of protein expression in the adult rat brain.
        J Neurosci Methods. 2012; 203: 354-360
        • Koob G.F.
        • Le Moal M.
        Drug abuse: Hedonic homeostatic dysregulation.
        Science. 1997; 278: 52-58
        • Moorman D.E.
        • Aston-Jones G.
        Orexin-1 receptor antagonism decreases ethanol consumption and preference selectively in high-ethanol–preferring Sprague-Dawley rats.
        Alcohol. 2009; 43: 379-386
        • Smith R.J.
        • See R.E.
        • Aston-Jones G.
        Orexin/hypocretin signaling at the orexin 1 receptor regulates cue-elicited cocaine-seeking.
        Eur J Neurosci. 2009; 30: 493-503
        • American Psychiatric Association
        Diagnostic and Statistical Manual of Mental Disorders.
        5th ed. American Psychiatric Publishing, Arlington, VA2013
        • Koob G.F.
        • Le Moal M.
        Plasticity of reward neurocircuitry and the “dark side” of drug addiction.
        Nat Neurosci. 2005; 8: 1442-1444
        • Vanderschuren L.J.
        • Everitt B.J.
        Drug seeking becomes compulsive after prolonged cocaine self-administration.
        Science. 2004; 305: 1017-1019
        • Kippin T.E.
        • Fuchs R.A.
        • See R.E.
        Contributions of prolonged contingent and noncontingent cocaine exposure to enhanced reinstatement of cocaine seeking in rats.
        Psychopharmacology. 2006; 187: 60-67
        • Mantsch J.R.
        • Yuferov V.
        • Mathieu-Kia A.M.
        • Ho A.
        • Kreek M.J.
        Effects of extended access to high versus low cocaine doses on self-administration, cocaine-induced reinstatement and brain mRNA levels in rats.
        Psychopharmacology. 2004; 175: 26-36
        • Knackstedt L.A.
        • Kalivas P.W.
        Extended access to cocaine self-administration enhances drug-primed reinstatement but not behavioral sensitization.
        J Pharmacol Exp Ther. 2007; 322: 1103-1109
        • Ben-Shahar O.
        • Posthumus E.J.
        • Waldroup S.A.
        • Ettenberg A.
        Heightened drug-seeking motivation following extended daily access to self-administered cocaine.
        Prog Neuropsychopharmacol Biol Psychiatry. 2008; 32: 863-869
        • Wee S.
        • Mandyam C.D.
        • Lekic D.M.
        • Koob G.F.
        Alpha 1-noradrenergic system role in increased motivation for cocaine intake in rats with prolonged access.
        Eur Neuropsychopharmacol. 2008; 18: 303-311
        • Schmeichel B.E.
        • Herman M.A.
        • Roberto M.
        • Koob G.F.
        Hypocretin neurotransmission within the central amygdala mediates escalated cocaine self-administration and stress-induced reinstatement in rats.
        Biol Psychiatry. 2017; 81: 606-615
        • Boutrel B.
        • Kenny P.J.
        • Specio S.E.
        • Martin-Fardon R.
        • Markou A.
        • Koob G.F.
        • et al.
        Role for hypocretin in mediating stress-induced reinstatement of cocaine-seeking behavior.
        Proc Natl Acad Sci U S A. 2005; 102: 19168-19173
        • McGregor R.
        • Shan L.
        • Wu M.F.
        • Siegel J.M.
        Diurnal fluctuation in the number of hypocretin/orexin and histamine producing: Implication for understanding and treating neuronal loss.
        PLoS One. 2017; 12: e0178573
        • Mileykovskiy B.Y.
        • Kiyashchenko L.I.
        • Siegel J.M.
        Behavioral correlates of activity in identified hypocretin/orexin neurons.
        Neuron. 2005; 46: 787-798
        • Horvath T.L.
        • Gao X.B.
        Input organization and plasticity of hypocretin neurons: Possible clues to obesity’s association with insomnia.
        Cell Metab. 2005; 1: 279-286
        • Lutter M.
        • Krishnan V.
        • Russo S.J.
        • Jung S.
        • McClung C.A.
        • Nestler E.J.
        Orexin signaling mediates the antidepressant-like effect of calorie restriction.
        J Neurosci. 2008; 28: 3071-3075
        • Zhou Y.
        • Cui C.L.
        • Schlussman S.D.
        • Choi J.C.
        • Ho A.
        • Han J.S.
        • et al.
        Effects of cocaine place conditioning, chronic escalating-dose “binge” pattern cocaine administration and acute withdrawal on orexin/hypocretin and preprodynorphin gene expressions in lateral hypothalamus of Fischer and Sprague-Dawley rats.
        Neuroscience. 2008; 153: 1225-1234
        • Moorman D.E.
        • James M.H.
        • Kilroy E.A.
        • Aston-Jones G.
        Orexin/hypocretin neuron activation is correlated with alcohol seeking and preference in a topographically specific manner.
        Eur J Neurosci. 2016; 43: 710-720
        • Yeoh J.W.
        • James M.H.
        • Jobling P.
        • Bains J.S.
        • Graham B.A.
        • Dayas C.V.
        Cocaine potentiates excitatory drive in the perifornical/lateral hypothalamus.
        J Physiol. 2012; 590: 3677-3689
        • Yeoh J.W.
        • James M.H.
        • Adams C.D.
        • Bains J.S.
        • Sakurai T.
        • Aston-Jones G.
        • et al.
        Activation of lateral hypothalamic group III metabotropic glutamate receptors suppresses cocaine-seeking following abstinence and normalizes drug-associated increases in excitatory drive to orexin/hypocretin cells.
        Neuropharmacology. 2018; ([published online ahead of print Sep 22])
        • Baimel C.
        • Lau B.K.
        • Qiao M.
        • Borgland S.L.
        Projection-target-defined effects of orexin and dynorphin on VTA dopamine neurons.
        Cell Rep. 2017; 18: 1346-1355
        • Mahler S.V.
        • Smith R.J.
        • Aston-Jones G.
        Interactions between VTA orexin and glutamate in cue-induced reinstatement of cocaine seeking in rats.
        Psychopharmacology. 2013; 226: 687-698
        • James M.H.
        • Charnley J.L.
        • Levi E.M.
        • Jones E.
        • Yeoh J.W.
        • Smith D.W.
        • et al.
        Orexin-1 receptor signalling within the ventral tegmental area, but not the paraventricular thalamus, is critical to regulating cue-induced reinstatement of cocaine-seeking.
        Int J Neuropsychopharmacol. 2011; 14: 684-690
        • Bernstein D.L.
        • Badve P.S.
        • Barson J.R.
        • Bass C.E.
        • España R.A.
        Hypocretin receptor 1 knockdown in the ventral tegmental area attenuates mesolimbic dopamine signaling and reduces motivation for cocaine.
        Addict Biol. 2018; 23: 1032-1045
        • Espana R.A.
        • Melchior J.R.
        • Roberts D.C.
        • Jones S.R.
        Hypocretin 1/orexin A in the ventral tegmental area enhances dopamine responses to cocaine and promotes cocaine self-administration.
        Psychopharmacology. 2011; 214: 415-426
        • James M.H.
        • Yeoh J.W.
        • Graham B.A.
        • Dayas C.V.
        Insights for developing pharmacological treatments for psychostimulant relapse targeting hypothalamic peptide systems.
        J Addict Res Ther. 2012; S4: 008