Objective      To explore the effect of early chronic life stress on aggressive behavior and expression of brain-derived neurotrophic factor (BDNF) of ventromedial hypothalamus nucleus and prefrontal cortex in puberty rats.       Methods      Twenty rats were randomly divided into 2 groups: an experimental group and a control group. The rats of the experimental group were given a series of stress including social isolation

reversal of day and night

social stimulation and resident-intruder confrontation at the 21st day after birth for 3 weeks. The expression of BDNF in ventromedial hypothalamus nucleus and prefrontal cortex was determined by immunohistochemistry.       Results       The  attack/threat (A/T) ratio (12.45±9.27

10.84±4.93) and duration of attack manifestations (DAM)(333.10±76.34

322.20±57.67) in resident-intruder test and neutral arena test increased significantly in the experimental group as compared with the control group (P0.01)

while the latency of the first attack (15.20±11.07

18.30±11.32 s) decreased significantly (P0.01). Moreover

the rats of experimental group exhibited violence behavior. Compared with the control group

the expression of BDNF elevated significantly in ventromedial hypothalamus nucleus (0.20±0.09

P0.05)

and decreased significantly in prefrontal cortex (0.19±0.08

P0.05) in the experimental group.       Conclusion       The violence behavior in puberty rats induced by early chronic life stress may be associated with the altered expression of BDNF in ventromedial hypothalamus nucleus and prefrontal cortex.