OBJECTIVETo establish social stress induced depression-like model in mice of C57BL/6 strain, and to assess its reliability using differenf behavioral methods.

METHODSTotally 20 male mice of C57BL/6 strain were divided into the normal group and the stress model group by random digit table,10 in each group. Another 10 CD1 mice were subjected to social stress. Mice in the normal control group received no stress, while those in the model group received social stress for 10 successive days. Behavioral assessment was performed using social interaction test (SIT), the elevated plus-maze (EPM) test, tail suspension test (TST), respectively. Serum cortisol level was detected by ELISA to assess the reliability of the model.

RESULTSIn the social interaction test when the social target (CDI mice) was inexistent, mice in the normal control group spent longer time in the social interaction zone and less time in the corner zone (P < 0.05); mice in the model group spent less time in the social interaction zone and more time in the corner zone (P < 0.05). Compared with the normal group when CDI mice existed, mice in the model group spent less time in the social interaction zone and more time in the corner zone (P < 0.05). Compared with the normal control group, the total times for entry into open arms, close arms, and the maze were obviously reduced (P < 0.05), and the proportion of entering open arms was significantly reduced (P < 0.05) in the model group. In TST, the motionless time within the last 4 mm was prolonged in the model group (P < 0.05). The serum cortisol level in the model group was obviously elevated (P < 0.01).

CONCLUSIONSocial stress induced depression-like animal model in mice of C57BL/6 straineasquite reliable and possibly suitable to be used in integrative medicine research of combination of disease and syndrome model.