Objective: To investigate the antidepressant-like effect of water extract of Acori Tatarinowii Rhizoma (WERAT)and its mechanism on the nervous system. Method: In the learned helplessness test

rats were divided randomly into five group: control group

non helpless group

imipramine(100 mg·kg-1) and WERAT (100

200 mg·kg-1). The test was administered via the oral rout

and using computer-aided controlling image analysis system for shuttle box

the rats were exprosured to inescapable footshock(IS) for the learned helplessness model. Then the conditioned avoidance testing was processed and the times of escape failure(EF) were recorded. In addition

mice were divided randomly into five groups: control group

fluoxetine (30 mg·kg-1) and WERAT(50

100

200 mg·kg-1). 5-hydroxy-DL-tryptophan(5-HTP) induced the head-twitch number of mice were investigated by the accentuation of 5-HTP test. Result: In the learned helplessness test

compared with the control group

the times of EF of IS rats were significantly increased from days 3-5(P<0.05

P<0.01

P<0.01)

WERAT at dose of 100 mg·kg-1 per day significantly reversed the effect of IS on EF from days 3-5(P<0.05

P<0.01

P<0.05)

and WERAT at dose of 200 mg·kg-1 per day also more significantly reversed the effect of IS on EF from days 3-4(P<0.01);WERAT could distinctly increased the frequency of head-twitch in the 5-HTP induced head-twitches test. Conclusions: The results of this study demonstrate that WERAT possesses significant antidepressant-like effect in the learned helplessness mode and its mechanism may be related to enhance the function of 5-hydroxytryptamine nerve systems.