Activation of Smads signal pathway in kidney of STZ-induced diabetic nephropathy rats

ObjectiveTo study the role of positive feedback factor Smad2 and its activated form Psmad2 in TGF-β/Smad pathway during the development of renal fibrosis in diabetic nephropathy.MethodsThirty SpragueDawley rats injected with streptozotocin(STZ) were randomly divided into 4W,8W,16W groups,other ten normal rats were used as controls.The systolic blood pressure,serum creatinine,24 hours urine volume,ratio of KW(kidney weight) to BW(body weight) were measured.ELISA was used to quantify 24 h urine protein.Renal injury was also assessed by kidney pathology.The expression of Smad2 and Psmad2 were detected by immunohistochemical method and Western blotting.ResultsThere was no statistical difference in Smad2 between 4W group and normal group(P 0.05) but a significant difference was found with control group from the 8th week on(P 0.05).Psmad2 increased from the 4th week on compared with control group(P 0.05).There was an increasing tendency in both proteins with the passage of time(P 0.05).ConclusionsThe results indicate that Smad2 pathway is involved in pathophysiological process of diabetic nephropathy.It may be one of the important pathways in diabetic renal fibrosis through activation of Smad2,upregulation of Smad2 expression,activation of Smad2 again.