Effect of early life chronic stress on spatial learning and memory and hippocampus brain-derived neurotrophic factor and 5-HT in puberty pathological aggression rats

Objective To explore the effect of early life chronic stress on spatial learning and memory and hippocampus brain-derived neurotrophic factor (BDNF) and 5-HT levels in puberty pathological aggression rats. Methods Twenty 21-day- old male rats were evenly randomized into 2 groups: experimental group and control group. Animals in the experimental group, from the early life till puberty, were given a series of stresses, including social isolation, reversed night and day, frustration test of non-reward, and resident intruder confrontations, etc. Resident intruder experiment was used to examine the aggressiveness of the animals; water maze experiments were performed to observe their spatial learning and memory. Immunohistochemistry method was used to test the expression of BDNF and 5-HT in the hippocampus. Results Morris water maze test showed that the total distance of theexperimental group was significantly longer than that of the control group (P>0. 05), and the experimental group had significantly less crossing times of hidden platform and escape latency compared with the control group (P<0. 05); the ratios of central area distance/total distance were similar in the two groups. Immunohistochemistry findings showed that BDNF and 5-HT positive neurons were significantly less in the hippocampus of experimental group compared with the control group (P<0. 05), and hippocampal BDNF and 5-HT expression in the experimental group was decreased. Conclusion BDNF and 5-HT may participate in the regulation of spatial learning and memory in the puberty pathological aggression rats, and they may play an important regulating role in spatial learning and memory.