Abstract: Objective To explore the effect and mechanism of Simplified Chaihu-Shugan Powder(SCSP) on hydroxytryptamine and tryptophan hydroxylase 2 in raphe nucleus of depressive rats. Methods Forty SD rats were divided into control group, model group, fluoxetine group, and SCSP group by randomized block design, with 10 rats in every group. Reserpine were intraperitoneal injected for 14 days to establish depressive models, and then the rats were seperatedly treated with the fluoxetine and SCSP. At the end of the experiment,behavioral experiments (sucrose preference test, forced swimming test) were performed to evaluate the depressive status. The contents 5-hydroxytryptamine (5-HT) in raphe nucleus were detected with high performance liquid chromatography-electrochemical detector (HPLC-ECD). The contents of tryptophan hydroxylase 2 (TPH2) in raphe nucleus were detected with real-time quantitative polymerase chain reaction(RT-PCR). Results Comparing to the control group, the body weight, weight gain, sucrose preference in model group decreased significantly (P<0.01), whilst the immobility time increased significantly (P<0.01). The contents of TPH2 and 5-HT in raphe nucleus decreased significantly (P<0.01) in model group. Comparing to the model group, the body weight, weight gain in SCSP group increased significantly (P<0.01), the sucrose preference increased (P<0.05), whilst the immobility time in SCSP group decreased significantly (P<0.01). The contents of TPH2 and 5-HT in raphe nucleus increased significantly (P<0.01) in fluoxetine and SCSP group. Conclusion SCSP showed anti-depression effect on the depressive rats caused by reserpine. It has same effect as fluoxetine. It could increase the content of TPH2 in raphe nucleus and promote the generation of 5-HT, which may be one of the mechanisms of anti-depression by SCSP.

Key words: Simplified Chaihu-Shugan Powder, reserpine, 5-hydroxytryptamine, tryptophan hydroxylase 2