Objective: To investigate the protective effects and mechanism of Chaihu Shugan powder (CHSGS) on hepatic fibrosis in rats. Method: Sixty Wistar rats were randomly divided into 6 groups:normol group

model group

Chaihu Shugan powder high-dose

mediate-dose

low-dose

and prevention group

except the normol group

all the other groups were injected with pig's serum without inactivation into abdominal cavity

twice per week and 0.5 mL each time

persisting for 10 weeks. The prevention groups were injected the stomach with the medicines(Chaihu Shugan powder 6.3 g·kg-1

10 weeks)at the same time when models began to be made

the other treatment groups were dealed with just as the prevention groups 6 weeks later persisting for 4 weeks. Then rats were randomly taken for decollation in all 6 groups at the end of 10th week. Chaihu Shugan powder high-dose group 12.6 g·kg-1

mediate-dose group 6.3 g·kg-1

low-dose group 3.15 g·kg-1. RT-PCR assay were used to detect the expression of transforming growth factor-β1(TGF-β1)

Smad2

Smad3

Smad4 and Smad7mRNA. The expression of TGF-β1

p-Smad 2/3 and Smad7 protein in hepatic fibrosis tissues was detected by immunohistochemical techniques. Result: The expression of TGF-β1

Smad2

Smad3 mRNA and the expression of TGF-β1

p-Smad 2/3 protein were markedly higher

while the expression of Smad7 gene were significantly lower in the model group than those in normal group(P<0.01). Compared with the model group

the expression of TGF-β1 and Smad3 mRNA were markedly lower

but the expression of Smad7 gene were significantly higher

the expression of p-Smad 2/3 and TGF-β1 protein were markedly lower(P<0.05

P<0.01)in Chaihu Shugan powder mediate-dose group. Conclusion: Chaihu Shugan powder have a positive action on hepatic fibrosis model rats.The mechanism of its effect is related with its inhibiting the expression of TGF-β1

Smad3 genes

and p-Smad 2/3 protein

and enhancing the expression of Smad7 gene in rats liver.