To Explore The Effects Of Tacrolimus On The Expression Of TRPC6 In The Kidney Of Rats With Type 2 Diabetes Mellitus

Objective: To investigate the expression of Nephrin 、 canonical transient receptor potential cation channel 6(TRPC6) in the kidney of rats with diabetic kidney desease(DKD) and the effects of tacrolimus on the expression of Nephrin、TRPC6. To explore the possible role of Nephrin、TRPC6 in the proteinuria and the renoprotective pathogenesis in DKD.Method: Forty normal male Wistar rats were randomly divided into two groups. The normal control groups(which fed normal diet) and the experimental groups, which fed with high-sucrose-high-fat-diet,after 8 weeks jnjected with a low dose of streptozotocin(STZ, 30mg/kg) into abdominal cavity to induce hyperglycemia, then sussessfully established type 2 diabetic models. Then the experimental groups were divided into two groups: DKD group and FK group(FK506, 0.5mg.kg-1d-1). Body weight、systolic blood pressure 、fasting blood glucose、fasting serum insulin、cholesterol、triglyceride, serum creatinine 、AST、ALT 、urinary albumin excretion and blood routine examination were detected at injection of STZ before and after one week, drug intervention of 0, 4, 8, 12 weeks. Rats were scarificed at 12 weeks, kidney index of rats and endogenous creatinine clearance were measured. Renal histomorpholygy was observed by light microscopy and transmission election microscope. The expression of Nephrin、TRPC6 were detected by RT-PCR and Western-blot.Result: There were 30 model rats, 22 were successfully established type 2 diabetes rats,the successful rate were 73%. Compared with NC group, the expressions of TRPC6 were significantly elevated(P<0.01), while the expression of nephrin was decreased(P<0.01);fasting blood glucose, fasting serum insulin,cholesterol, triglyceride, endogenous creatinine clearance, urinary albumin excretion, KW/BW index and creatinine clearance rate were significantly increased(P<0.01). Compared with DKD group, TRPC6 expression were markedly downregulated by tacrolimus(P<0.01), while nephrin expressions were effectively upregulated(P<0.01), and the urinary albumin excretion、KW/BW index were significantly decreased(P<0.01). Under light microscopy, DKD group was characterized by glomerular volume increasing, GBM thickening, mesangial cell proliferation; after FK506 treatment, the severity of pathological damages was clearly ameliorated. The result of election microscope showed that podocytes were tumefied and foot processes were fusioned into a band and aldered to the basement membrane,whereas the abnormal histomorphology changes were improved in FK group.Conclusions: The abnormal expressions of Nephrin、TRPC6 leaded to the injury of podocytes and damaged glomerular filtration membrane structure and barrier functional integrity, to participate in development process of DKD. Tacrolimus may decrease TRPC6 expression and increase Nephrin expression to reduce the DKD.