The Inhibitive Effect And Mechanisms Of Rosiglitazone On The Lung Fibrosis Induced By Paraquat In Rats

Purpose:Paraquat is a non-selective herbicide which is widely used in agriculture.It has potential of producing pulmonary fibrosis.Rosiglitazone is a member of the thiazolidinedione?TDZ?family,and is a ligand for peroxisome proliferator-activated receptor-??PPAR-??.Rosiglitazone is used clinically for the treatment of type 2diabetic patients due to its insulin-sensitizing effects.Recent studies have indicated that PPAR-?agonists inhibit TGF-?induced pulmonary myofibroblast differentiation and collagen production.However,whether rosiglitazone can inhibit PQ-induced acute lung fibrosis remains unknown.We construct a rat lung fibrosis model induced by the paraquat,then we use rosiglitazone to treat the rat.The purpose of our study is to investigate the effects of the PPAR-?agonist rosiglitazone on the acute lung fibrosis induced by paraquat?PQ?and the underlying mechanisms of action.The results may lead to the use of rosiglitazone as a treatment for PQ-induced acute lung fibrosis.Methods:1.The construction of rat fibrosis model induced by the paraquat70 Sprague Dawley rats were divided into seven groups including the normal control group and the 20,25,30,35,40 and 45 mg/kg group.After adapting to the environment,the rats were intraperitoneally administered PQ at doses of 20,25,30,35,40 and 45mg/kg.Cumulative PQ mortalities were observed at the 4 week after PQ administration.We calculate the LD50,and the PaO₂,the W/D ratio,the fibrosis score of the lung,finally we got the proper dose of the model.2.To investigate PPAR-?expression level in the acute lung fibrosis induced by paraquat.50 Sprague Dawley rats were divided into five groups including the normal control group and 7 day,14 day,21 day,28 day paraquat group.We investigate the expression level of PPAR-?,PTEN,TGF-?1,?-SMA in the lung tissue.3.To investigate underlyng mechanism of the effect of rosiglitazone on the acute lung fibrosis induced by paraquat.60 Sprague Dawley rats were devided into six groups including the normal control group and the paraquat group and the paraquat+rosiglitazone group,the rosiglitazone group,the paraquat+rosiglitazone+GW9662 group,the GW9662 group.We calculate the PaO₂,the W/D ratio,the fibrosis score of the lung tissue,the protein?Western blot method?and mRNA?RT-PCR?expression of PPAR-?,PTEN,TGF-?1,?-SMA in the lung tissue were observed at the 4 week after PQ administration.Analyze the inhibitive effect of rosiglitazone on the acute lung fibrosis induced by paraquat4.To investigate underlying mechanism of the effect of rosiglitazone on the A549exposed to paraquat.This study divide the A549 cell into 4 group including the normal control group,the paraquat group,the paraquat+rosiglitazone group,the paraquat+rosiglitazone+GW9662group.The proliferative activity of A549 cells via MTT assay,the concentration of hydroxyproline in the supernatant and the PPAR-?,PTEN,TGF-?1,?-SMA expression of the A549 cells via western-blot were detected and analyzed.Results:1.This study construct the lung fibrosis rat model at different doses.This study found that with the increase of paraquat dosage,the mortality of rats,the pulmonary fibrosis score,the lung wet to dry weight ratio of the rats lung tissue increased gradually,while the PaO₂ decreased gradually.Finally we choose the dose of 30mg/kg,which has a low mortalities and high fibrosis score.2.We observed the paraquat induced pulmonary fibrosis model of rats.Results showed that with the extension of time,pulmonary fibrosis score in rats lung tissue,lung wet to dry weight ratio increased gradually,PaO₂ decreased gradually,the expression of PPAR-?,PTEN decreased,the?-SMA,TGF-?1 increased gradually.3.The expression of the PPAR-?,PTEN protein and mRNA level in the paraquat group is lower than the control group.The expression of the PPAR-?,PTEN protein and mRNA level in the paraquat+rosiglitazone group is higher than the paraquat group.The expression of the PPAR-?,PTEN protein and mRNA level in the paraquat+GW9662group is similar to the paraquat group,and is lower than the paraquat+rosiglitazone group.The expression of TGF-?1,?-SMA is opposite to the PPAR-?,PTEN.4.The proliferative activity of A549 cells in the paraquat+rosiglitazone group is higher than the paraquat group.The concentration of hydroxyproline in the supernatant of the paraquat+rosiglitazone group is lower than the paraquat group.The expression of the PPAR-?,PTEN protein in the paraquat group is lower than the control group,the expression of the PPAR-?,PTEN protein level in the paraquat+rosiglitazone group is higher than the paraquat group,the expression of the PPAR-?,PTEN protein level in the paraquat+rosiglitazone+GW9662 group is similar to the paraquat group,and is lower than the paraquate+rosiglitazone group.The expression of TGF-?1 and?-SMA is opposite to the expression of PPAR-?and PTEN.Conclusion:1.We can construct the lung fibrosis rat model at he dose of 30 mg/kg on the 28 day2.With the extension of time,the pulmonary fibrosis score and the lung wet to dry weight ratio of paraquat group increased gradually,the expression of PPAR-?and PTEN decreased,the expression of?-SMA and TGF-?1 increased gradually.3 Rosiglitazone have inhibitive effect on the lung fibrosis induced by the paraquat.The inhibitive effect of the rosiglitazone may be caused by activation of the PPAR-?,upregulating of PTEN,downregulating of TGF-?1 pathway.4 Rosiglitazone have protective effect on A549 cell exposed to paraquat.The protective effect of the rosiglitazone may be caused by activating of the PPAR-?,upregulating of PTEN,downregulating of the TGF-?1 pathway.