ラットにおける海馬機能およびタンパク質発現に対する母子分離の影響

Recent studies demonstrated that early adverse experiences induce long-lasting functional and neurochemical alternation in the brain. The aim of this study was to identify the influence of neonatal isolation (NI) on hippocampal function and protein expression. We examined the influence of NI on fear conditioning (FC) with other behavioral assessments (open field test and elevated plus maze) in adolescent rats. Rats subjected to NI showed the significant decreases in contextual freezing compared with sham-treated rats on day 2 and 3, but not on day 4. There were no significant differences in locomotor activity and anxiety between rats with sham treatment and NI. Next, I examined the influence of NI on hippocampal protein expression. As compared with sham-treated rats, the levels of integrin β3 were significantly reduced in the rats subjected to NI before FC and after 3 and 4-day exposure to FC. These findings suggest that the decrease in hippocampal integrin β3 levels may, at least in part, play a role in the impairment of hippocampal-dependent memory. In addition, dissociation between contextual freezing and integrinβ3 on day 4 implied that the recovery of the impairment of hippocampal-dependent memory induced by NI may be modulated by other mechanisms.