| ObjectiveThe study was designed 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.Methods90 adult healthy male Wister rats were randomly devided into three groups of different treatments designed as: Control n=10, PQ alone (PQ) n=40, Curcumin treatment (Cur) n=40.Each group was devided into 5 subgroups.The animals were killed either 1,3,7,14or21days after PQ administration.The rats in PQ group and Cur group were treated with intragastrically (i.g.) with PQ (50mg·kg-1) and the rats in Control group were treated with the same dose of distilled water at the beginning of the experiment.The Cur group received curcumin (200mg·kg-1 ,i.p.) once a day after PQ administration and the other two groups received saline.At the given timepoints, animals were sacrified and lungs were harvested.The body weight lung wet weight of rats were measured and lung index of rats in each group were compared. Pathology of lung tissue were observed by HE staining and Masson staining .Hydroxyproline in lung tissue were used to determine the severity of pulmonary fibrosis .The expression of TGF-β1 and c-Jun in lung tissue were detected by immunohistochemistry staining.Results(1) Intoxication manifestation : The intoxication manifestation of PQ group was much more serious than that of Cur group.The effects were association with 66.67% survival of Cur group rats in comparison with 35% survival in rats exposed to PQ only.(2) HE staining :Pulmonary edama,hemorrhage or extrusion of inflammatory cells were seen in PQ group, especially during the first 3 days. We observed proliferation of collagen fibers and fibrous thickening of the alveolar wall 14-21 days after PQ intoxication.Curcumin can relieve the lung inflammation and fibrosis in our study.(3) Masson staining :In control group there were a small quantity of collagen fibers stained green or blue on the bronchus dissepiment and the septal surface. As the same as HE staining, proliferation of the stained collagen fibers and thickness of the alveolar wall were seen in PQ group and no significant amelioration of fibrosis were found in Cur group.(4) Hydroxyproline: Compared with PQ group ,the level of HYP of Cur group were significant lower at 21 day after PQ exposed.(5) Immunohistochemistry staining :The intensity of the expression TGF-β1 was significantly higher in PQ group than that in the other two group at 7d ,14d and 21d after PQ exposure. There's no difference of TGF-β1 expression between Control group and Cur group. c-Jun expression in PQ group and Cur group were both significantly increased during the early period (1d,3d) compared with Control group.The expression of c-Jun in Cur group was the same as that of the Control group,while level of c-Jun in PQ group was still higher.Conclusion(1) AP-l and TGF-β1 may be involved in the process of pulmonary fibrosis in PQ poisoning.(2) Curcumin had an inhibitory effect on paraquat-induced pulmonary fibrosis ,and the effect may be due to inhibition of TGF-β1,but the details of its effects are still unknown.
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