Premium
Relationship between post‐traumatic stress disorder‐like behavior and reduction of hippocampal 5‐bromo‐2′‐deoxyuridine‐positive cells after inescapable shock in rats
Author(s) -
Kikuchi Akihito,
Shimizu Kunio,
Nibuya Masashi,
Hiramoto Takeshi,
Kanda Yasunari,
Tanaka Teppei,
Watanabe Yasuhiro,
Takahashi Yoshitomo,
Nomura Soichiro
Publication year - 2008
Publication title -
psychiatry and clinical neurosciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.609
H-Index - 74
eISSN - 1440-1819
pISSN - 1323-1316
DOI - 10.1111/j.1440-1819.2008.01875.x
Subject(s) - subgranular zone , neurogenesis , hippocampal formation , hippocampus , neuroscience , learned helplessness , psychology , bromodeoxyuridine , endocrinology , medicine , progenitor cell , immunohistochemistry , stem cell , biology , clinical psychology , subventricular zone , genetics
Aim: Inescapable shocks (IS) have been reported to reduce the number of 5‐bromo‐2′‐deoxyuridine (BrdU)‐positive cells in hippocampus. Antidepressants prevent this reduction, and the role of neurogenesis in depression is now suggested. It has been reported, however, that the number of BrdU‐positive cells was not different between the rats that developed learned helplessness and those that did not. This suggests that reduction of neurogenesis does not constitute a primary etiology of depression. It has been previously shown that IS can cause various post‐traumatic stress disorder (PTSD)‐like behavioral changes in rats. The aim of the present was therefore to examined whether the reduction of BrdU‐positive cells relates to any PTSD‐like behavioral changes in this paradigm. Methods: Rats were given either inescapable foot‐shocks (IS) or not shocked (non‐S) treatment in a shuttle box on day 1 and received BrdU injections once daily during the first week after IS/non‐S treatment. On day 14, rats treated with IS and non‐S were given an avoidance/escape test in the shuttle box and dorsal hippocampal SGZ were analyzed by BrdU immunohistochemistry. Results: In accordance with previously reported results, IS loading resulted in fewer BrdU‐positive cells in the hippocampal subgranular zone (SGZ). Furthermore, in the IS‐treated group, the number of BrdU‐positive cells in the hippocampal SGZ was negatively correlated at a significant level with several hyperactive behavioral parameters but not with hypoactive behavioral parameters. Earlier findings had indicated that chronic selective serotonin re‐uptake inhibitor administration, which is known to increase hippocampal neurogenesis, restored the increase in hypervigilant/hyperarousal behavior but did not attenuate the increase in numbing/avoidance behavior. Conclusion: The regulatory mechanism responsible for the decreased proliferation and survival of cells in the hippocampus may be related to the pathogenic processes of hypervigilance/hyperarousal behaviors.