Effects of Chaihu Shugan San on behavior and plasma levels of corticotropin releasing hormone and adrenocorticotropic hormone of rats with chronic mild unpredicted stress depression

Abstract

To investigate the effects of Chaihu Shugan San (CHSGS), a compound traditional Chinese herbal medicine, on behavior and plasma levels of corticotropin releasing hormone (CRH) and adrenocorticotropic hormone (ACTH) of rats with chronic mild unpredicted stress depression. Forty male Sprague-Dawley rats were randomly divided into 4 groups: normal control group, untreated group, fluoxetine group and CHSGS group. Except the normal control group, rats were singly housed and exposed to an unpredicted sequence of mild stressor for continuous 4 weeks to induce depression. Since the fifteenth day, rats were intragastrically administered with equal volume agents respectively for 2 weeks [normal saline for the normal control group and the untreated group, fluoxetine (1.8 mg/kg) for the fluoxetine group and CHSGS (5.9 g/kg) for the CHSGS group]. Behavioral scores of rats were detected by open-field test and sucrose preference test, and the plasma levels of CRH and ACTH in different groups were detected by radioimmunoassay. Compared with the normal control group, body weights of the rats in the untreated group were significantly decreased. Scores of crossing, rears and grooming in open-field test were reduced significantly. Pure water consumption in sucrose preference test was increased significantly. The levels of plasma CRH and ACTH were significantly increased. The depressive behaviors of the rats were improved significantly and the levels of plasma CRH and ACTH were obviously reduced in the CHSGS group. Chronic mild unpredicted mild stress can affect the neuroendocrine and behavior and cause depression in rats. CHSGS can regulate HPA hyperactivity of rats caused by chronic stress and has antidepressive effects.