Xiaoyaosan regulates depression-related behaviors with physical symptoms by modulating Orexin A/OxR1 in the hypothalamus.

The functional regulation of the orexin system in the central nervous system is closely related to the occurrence and development of psychotic disorders. Abnormal changes in the lateral region of the hypothalamus are associated with the comorbidity of depression and physical symptoms, and how the traditional Chinese formula Xiaoyaosan regulates these changes may reveal aspects of the pathogenesis of depression. This study aimed to establish a rat model of depression in order to examine changes in Orexin A/OxR1 expression in the lateral region of the hypothalamus and the effects of Xiaoyaosan. Sixty specific pathogen-free (SPF) male healthy Sprague-Dawley (SD) rats were used in the experiment and randomly divided into the control group, the model group, the Xiaoyaosan group and the fluoxetine group. The depression model was established by 21-day chronic immobilization stress (CIS). Food intake and body weight were recorded, and the sucrose preference test (SPT) and open field test (OFT) were used to evaluate the model. Then, the expression of Orexin A/OxR1 in the hypothalamus was measured by ELISA, Western blot and quantitative real-time polymerase chain reaction (qRT-PCR) analysis. The expression of Orexin A and OxR1 in the lateral hypothalamic area was significantly down regulated in the model group, compared with the control group. Xiaoyaosan significantly reversed these changes with obvious curative effects. Abnormal changes in Orexin A/OxR1 in the lateral hypothalamic area of rats with depression caused by chronic stress are closely related to the pathogenesis of depression accompanied by physical symptoms. Xiaoyaosan can improve depression accompanied by physical symptoms by regulating Orexin A/OxR1.