Effects of Rho kinase inhibitor fasudil on paraquat-induced pulmonary fibrosis in rats

Abstract

Objective To investigate the effect of Rho kinase inhibitor, fasudil, on pulmonary fibrosis induced by paraquat in rats in order to elucidate the underlying mechanisms. Methods A total of 72 Sprague-Dawley male rats of specific pathogen free (SPF) were randomly(random number) divided into four groups: the normal control group (NS group, n=18), fasudil control group (FS control group, n=18), paraquat poisoning group (PQ poisoning group, n=18) and fasudil intervention group (FS intervention group, n=18). On days 7, 14, 28 after paraquat exposure, six rats were respectively selected from each group. These rats were anesthetized and sacrificed immediately, and their lung tissues were collected. The hydroxyproline (HYP) in the lung tissue was detected by using alkaline hydrolysis. The expressions of type Ⅰ, Ⅲ collagen protein, connective tissue growth factor (CTGF) and ROCK1 mRNA in Rho/ROCK signaling pathway were assayed by using the real-time quantitative PCR (RT-PCR), and the levels of type Ⅰ, Ⅲ collagen protein, connective tissue growth factor (CTGF) and Rho / ROCK signaling pathway ROCK1 protein were measured by using Western blotting. The pathological changes of lung tissue were observed under light microscope. Results There were no significant differences in the observed biomarkers between FS control group and NS group (P>0.05). While in PQ poisoning group and FS intervention group on days 7, 14, 28 (all P<0.05), the amount of HYP increased obviously (P<0.05), the expressions of type Ⅰ, Ⅲ collagen protein, CTGF, ROCK1 mRNA and protein levels were increased significantly (P<0.05). Compared with the PQ poisoning group, the amount of HYP decreased significantly, and the expressions of type Ⅰ, Ⅲ collagen protein, CTGF, ROCK1 mRNA and protein levels were decreased significantly in FS intervention group on days 7, 14, 28 (all P<0.05). The pathological changes of lung tissue revealed that the degree of pulmonary fibrosis in the PQ poisoning group were most serious on 28 d after paraquat exposure, and the degree of pulmonary fibrosis were lessened in FS intervention group on days 7, 14, 28. Conclusions ROCK inhibitor, fasudil, has obvious therapeutic effects on paraquat-induced lung fibrosis, by regulating Rho / ROCK signaling pathway with down-regulated expression of CTGF, and decrease in the levels of type Ⅰ, Ⅲ collagen protein, thus reducing protein deposition. Key words: Paraquat; Pulmonary fibrosis; Fasudil; Rho / ROCK signaling pathway