The Effect of Curcumin on the Expression of TGF-β_1 and c-Jun in the Rat Lung Injured by Paraquat

Objective To investigate TGF-β1 and c-Jun expression in the lungs of paraquat-poisoned rats and to evaluate the effect of curcumin on paraquat-induced pulmonary fibrosis.Methods Wistar rats were randomly divided into paraquat-poisoned group(PQ group,with PQ 50 mg/kg i.g) and curcumin-treated group (PC group,with PQ 50 mg/kg i.g and with curcumin 200 mg/kg,i.p.once a day) .At the given time points,animals were scarified with lungs harvested.The body weight and lung wet weight of rats were measured and lung indice of rats in each group were compared.Pathological appearances of lung tissue were observed by HE staining and Masson staining.Hydroxyproline(HYP) in lung tissue were used to determine the severity of pulmonary fibrosis.The expression of TGF-β1 and c-Jun in lung tissue were examined by immunohistochemistry.Results The survival rates of mice were 67% and 35% in the PC and PQ groups with significant difference (P 0.05).Pulmonary edama,hemorrhage or extrusion of inflammatory cells was observed in PQ group,especially during the first 3 days.After 14 d,the production of collagen fibers and fibrous thickening of the alveolar wall were seen in PQ intoxication.Curcumin could relieve the lung inflammation and fibrosis in our study.The level of HYP of PC group were significantly lower than that of PQ exposure after 14 d (P 0.05).The expression TGF-β1 was increased in PQ exposure after 7 d.The intensity of the expression TGF-β1 in PC group was significantly lower than that in PQ group after 14 d (P 0.05).After 1 d,the expression c-Jun in PQ group were not significantly higher than that in PC group (P 0.05).Conclusion Curcumin can relieve paraquat-induced collagen deposition and pulmonary fibrosis due to its inhibitory effect of TGF-β1 expression,but not c-Jun expression.