The purpose of this study was to investigate the effects of chronic social defeat stress (CSDS) on the behavior of mice and the underlying neuroendocrine mechanisms. The CSDS was carried out by "residence-intruder" model, in which the subjects (descendants of wild mice) were exposed to a larger group of aggressive Kunming male mouse for 10 min in 10 successive days. Open field test, social approach and avoidance test as well as tail suspension test were used to screen the susceptible and unsusceptible mouse. c-Fos expression differences were studied in the limbic brain areas among susceptible, unsusceptible and control groups. The serum corticosterone levels were studied by ELISA. Results showed that: only 39.1% of mouse showed depression-like behaviors when were exposed to CSDS; c-Fos expressions in the prefrontal cortex, hypothalamus paraventricular nucleus, medial amygdala and lateral habenular nucleus were significantly different among the three groups; serum corticosterone levels were significantly higher in susceptible group than those in the other two groups.The results indicated that the subjects could be divided into susceptible and unsusceptible subtypes when they were exposed to CSDS. The different sensitivity of HPA axis and activities in some brain areas of limbic system such as prefrontal cortex, hypothalamic paraventricular nucleus, amygdala and lateral habenular nucleus may play important regulation roles in these two subtypes.

social defeat; house mouse; stress; c-Fos; corticosterone