RESUMEN
Objective To observe the effectiveness and mechanism of Xiaoyao San (Xiaoyao Powder for Soothing Liver and Relieving Depression) in improving depression-like behavior of rats. Methods Male Wistar rats were randomized into normal group, model group, Xiaoyao San (1.9 g·kg-1·d-1) group, and fluoxetine (2 mg·kg-1·d-1) group. The rats were exposed to chronic unpredictable mild stress ( CUMS) to induce rat depression-like behavior. Field test was performed for the observation of effect of Xiaoyao San on rat depression-like behavior, Luminex liquid chip system was applied to detect the serum cytokines, and the amount and size of rat hepatic sinusoidal endothelial window were examined under electron microscope, and hepatic indoleamine 2, 3-dioxygenase ( IDO) and tryptophan 2, 3 -dioxygenaes ( TDO) expression levels were detected by immunohistochemical and Western blot methods. Results Xiaoyao San showed obvious effect on increasing sugar water consumption, the number of crossing the blocks and erection frequency in rats, decreasing serum levels of tumor necrosis factor alpha ( TNF-α) and interleukin 6 ( IL-6) , increasing the amount of hepatic sinusoidal endothelial window, promoting hepatic sinusoidal endothelial vascularization, and reducing TDO and IDO expression ( P<0.05 or P<0.01). Conclusion Xiaoyao San exerts obvious effect on improving rat depression-like behaviors, and the mechanism is probably related with the decrease of inflammatory factors, inhibition of IDO pathway, and improvement of hepatic sinusoidal endothelial function.