Effects of Chaihu Shugan San on behavior and CRHmRNA expression in the brain of mice with chronic mild unpredicted stress depression

Abstract

Objective To investigate the effects of Chaihu Shugan San(CHSGS) ,a compound traditional Chinese herbal medicine,on the behavior and plasma levels of corticosterone level and corticotrophin releasing hormone ( CRH) mRNA expression in the prefrontal cortex and the hypothalamus of mice with chronic mild unpredicted stress depression. Methods 40 adult male Kunming mice were randomly divided into 4 groups: the normal control group,the model control group,the fluoxetine group and CHSGS group. Except the normal control group, mice were exposed to an unpredicted sequence of mild stressor for continuous 21 days to induce depression. Since the 8th day, mice were intragastrically administered with equal volume agents respectively for 14 days (normal saline for the normal control group and the model group,fluoxetine(2. 6 mg · kg-1 ) for fluoxetine group and CHSGS (8.45 g · kg-1) for CHSGS group). Body weight and behaviors were investigated,the plasma levels of CORT in different groups were detected by radioimmunoassay, and the mRNA expression in the prefrontal cortex and the hypothalamus were semiquantified by the RT-PCR method. Results In comparision with the model group, body weight changes ( (13.22 ±3.57)g) and consumption of sucrose solution((1. 90 ±0. 74) ml) of CHSGS groups were significantly increased, and the duration of immobility during the forced swimming ((62.20±13.73)s) and tail suspension((58. 10 ± 11.71 )s) ,the levels of plasma CORT((12.61 ±4.63)ng/L) and the CRHmRNA expression in the prefrontal cortex(0.34 ±0.10) and the hypothalamus(0.70 ±0.09) were significantly decreased. Conclusion CHSGS can reverse the depressive behavior, reduced the levels of plasma CORT and down-regulated CRHmRNA expression in the prefrontal cortex and the hypothalamus of the depressive mouse caused chronic stress. Key words: Chaihu Shugan San; Stress; Mice; Behavior; Corticotrophin releasing hormone