Background
Changes in densities and in the morphology of dendritic spines in the hippocampus
are linked to hippocampal long-term potentiation (LTP), spatial learning, and depression.
Decreased brain-derived neurotrophic factor (BDNF) levels seem to contribute to depression.
Through its receptor trkB, BDNF is also involved in hippocampal LTP and hippocampus-dependent
learning. Conditionally gene-targeted mice in which the ablation of trkB is restricted
to the forebrain and occurs only during postnatal development display impaired learning
and LTP.
Methods
To examine whether there is a link among impaired hippocampal synaptic plasticity,
altered spines, and trkB receptors, we performed a quantitative analysis of spine
densities and spine length in the hippocampal area CA1 and the dentate gyrus in conditional
mutant mice (trkBlox/loxCaMKII-CRE mice). TrkB protein and mRNA levels were assayed using Western blot and
in situ hybridization analysis.
Results
Fifteen-week-old mutant mice exhibit specific reductions in spine densities and a
significant increase in spine length of apical and basal dendrites in area CA1. These
alterations correlate with a time- and region-specific reduction in full-length trkB
mRNA in the hippocampus.
Conclusions
TrkB functions in structural remodeling of hippocampal dendritic spines, which in
turn may affect synaptic transmission and plasticity.
Key Words
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Article info
Publication history
Published online: December 02, 2005
Accepted:
August 31,
2005
Received in revised form:
July 26,
2005
Received:
May 9,
2005
Identification
Copyright
© 2005 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.
