Abstract: 【Abstract】 Objective To observe The inhibitory effect of PNS on rat pulmonary fibrosis and to discuss the mechanism of this action.Method Divide 80 only rats randomly into the model group,PNS rental ,methylprednisolone group and the combined treatment group. Adopting bleomycin prepare pulmonary fibrosis in rats, 24 hours later ,give them medication every day,then kill those rats respectively at the 7th、14th、21th、28th day and observe its pathological changes by detecting the expression levels of ICAM-1, TGF-β1, MMP-9 in lung tissue.Results The PNS rental，methylprednisolone group and the combined treatment groups are no serious Alveolitis and pulmonary fibrosis.The expression levels of ICAM-1, TGF-B1, MMP-9 of PNS rental, methylprednisolone group, and the combined treatment group are significantly decrease compared with the model group（p<0.01）. The combined treatment group’s expression levels of TGF-β1 are lower than the two single medicine treatment group(p<0.05).Conclusion the PNS can effectly restrain pulmonary fibrosis process induced by bleomycin,and using corticosteroids together can reduce hormone dosage and side effects, while enhancing the treatment effect.

Key words: PNS, Pulmonary fibrosis, ICAM-1, TGF-B1, MMP-9