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Aging and depression vulnerability interaction results in decreased serotonin innervation associated with reduced BDNF levels in hippocampus of rats bred for learned helplessness
Author(s) -
Aznar Susana,
Klein Anders B.,
Santini Martin A.,
Knudsen Gitte M.,
Henn Fritz,
Gass Peter,
Vollmayr Barbara
Publication year - 2010
Publication title -
synapse
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.809
H-Index - 106
eISSN - 1098-2396
pISSN - 0887-4476
DOI - 10.1002/syn.20773
Subject(s) - learned helplessness , serotonin transporter , hippocampal formation , hippocampus , serotonin , psychology , neurotrophic factors , neuroscience , brain derived neurotrophic factor , depression (economics) , medicine , endocrinology , serotonergic , developmental psychology , receptor , economics , macroeconomics
Epidemiological studies have revealed a strong genetic contribution to the risk for depression. Both reduced hippocampal serotonin neurotransmission and brain‐derived neurotrophic factor (BDNF) levels have been associated with increased depression vulnerability and are also regulated during aging. Brains from young (5 months old) and old (13 months old) congenital Learned Helplessness rats (cLH), and congenital Non Learned Helplessness rats (cNLH) were immunohistochemically stained for the serotonin transporter and subsequently stereologically quantified for estimating hippocampal serotonin fiber density. Hippocampal BDNF protein levels were measured by ELISA. An exacerbated age‐related loss of serotonin fiber density specific for the CA1 area was observed in the cLH animals, whereas reduced hippocampal BDNF levels were seen in young and old cLH when compared with age‐matched cNLH controls. These observations indicate that aging should be taken into account when studying the neurobiological factors behind the vulnerability for depression and that understanding the effect of aging on genetically predisposed individuals may contribute to a better understanding of the pathophysiology behind depression, particularly in the elderly. Synapse 64:561–565, 2010. © 2010 Wiley‐Liss, Inc.