Effect of curcumin on bleomycin-induced pulmonary fibrosis in rats

Objective To study the inhibitory effects of curcumin on bleomycin-induced pulmonary fibrosis in rats at the fibrosing stage and explore its possible mechanism.Methods 96 male SD rats were randomly divided into a normal control group,a fibrosis model group,a fibrosis model treated with prednisone group and a fibrosis model treated with curcumin group.Pulmonary fibrosis were induced by instilled bleomycin through tracheal.From day 15 after bleomycin administration,the curcumin group and prednisone group were given curcumin(300 mg/kg) or prednisone(5 mg/kg) per day by intragastric administration,respectively.The normal control group and fibrosis model group were given 1% sodium carboxymethyl cellulose(10 mL/kg) as control.Six rats of each group were randomly sacrificed on day 21,28,42 and 56 after bleomycin administration,respectively.The histological changes of the lung were evaluated by HE and Masson's trichrome staining.Lung expressions of transforming growth factor-β1(TGF-β1) and hydroxyproline were assessed by immuno-histochemistry and digestion method,respectively.Results Pulmonary fibrosis and hydroxyproline level in the curcumin group were significantly reduced as compared with those in the model group on day 42 and 56.The expession of TGF-β1 in the curcumin group was significantly lower than that in the model group on day 28,42 and 56,and was not significantly different from the normal group on day 56.Conclusion Curcumin could alleviate bleomycin-induced pulmonary fibrosis in rats at the fibrosing stage by inhibiting the expressions of TGFβ1.