Objective: To study the antidepressant effect and mechanism of Yuxinxiao. Method: Mice were randomly divided into five groups as follows:the model group

positive control group

Yuxinxiao groups(320

640

1 280 mg·kg-1)

all groups were administered ig for 7 days

5-hydroxytryptophan(5-HTP)-induced head-twitch and yohimbine-induced lethality tests were used after the last administration to observe the impact of 5-HTP(10 mg·kg-1

iv) induced head twitch behavior and yohimbine-induced(35 mg·kg-1

sc) lethality in mice; rats were randomly divided into control group

model group

sertraline hydrochloride group(10 mg·kg-1)

Yuxinxiao groups(220

440

880 mg·kg-1).The chronic unpredictable mild stress model was established by continuous gavage 8 weeks

the sucrose preference degree

open-field behavior and the content of 5-HT

dopamine(DA) and norepinephrine(NE) in hippocampus were tested to evaluate the empact of Yuxinxiao on CUMS models. Result: Yuxinxiao(320

640

1 280 mg·kg-1

ig)ignificantly increased the frequence of 5-HTP(10 mg·kg-1

iv) induced head-twitch in mice after 7 days of continuous administrations while it did not enhance the yohimbine-induced(35 mg·kg-1

sc)lethality in mice. The contents of 5-HT and DA were increased remarkably in hippocampus of the model group treated with high dose of Yuxinxiao(880 mg·kg-1) after 8 weeks of continuous administrations compared with model groups. Conclusion: Yuxinxiao has a clear antidepressant effect with manner of dose-dependent. The mechanism may be related to the system of 5-HT in central nervous system.