Abstract: OBJECTIVE: To evaluate the effects of the Xiaoyaosan(XYS) decoction on the food intake and body weight of rats with chronic immobilization stress(CIS), as well as the concentration of serum leptin and the expression of feeding-related neuropeptides [leptin receptor(Ob-R), proopiomelanocortin(POMC), and α-melanocyte-stimulating hormone(α-MSH)] in the hypothalamic arcuate nucleus(ARC).METHODS: We subjected rats to CIS for 3 h a day.The rats were randomly divided into the following groups: control group, 7-day stress group, 21-day stress group and XYS-treated group. The rats in the two stress groups were exposed to CIS for 7 or 21 d.The rats in the XYS-treated group were also exposed to CIS for 21 d and were intragastrically administered the XYS decoction before stress. The body weight and food intake of the rats were measured every day. The content of leptin in serum andα-MSH in the ARC were detected by ELISA, and the expression of neuropeptides in the ARC was assayed by immunofluorescence, Western blot and q RT-PCR.RESULTS: The food intake and body weight of rats exposed to CIS were lower than those of control rats. The serum leptin, and expression levels of ObR, POMC and α-MSH in the ARC were significantly higher than those in the control rats. Treatment with the XYS decoction improved the appetite and the body weight, and down-regulated serum leptin and Ob-R, POMC and α-MSH in hypothalamus ARC.CONCLUSION: The leptin-Ob-R-POMC pathway might be the part of the mechanism underlying XYS's improvement of somatic symptoms such as reduction in food intake and body weight related to CIS.

Key words: Chronic immobilization stress, Xiao Yao San, Neuropeptides, Arcuate nucleus of hypothalamus, Eating