| Background: It is well known that diabetic nephropathy(DN)has become one of the most common causes of end stage renal disease(ESRD).About the patients with 30%-40%DN can develop into ESRD,and there is an increasing trend.In recent years,great progress has been made in the study of DN,but the incidence of DN continues to increase,and the therapeutic effect is poor.Therefore,new targeted drugs are urgently needed to alleviate the progression of DN.The main clinical manifestations of DN are persistent proteinuria and progressive deterioration of renal function.As an important part of glomerular filtration barrier,podocyte is associated with podocyte injury and proteinuria in the early stage of DN.In recent years,podocyte lesion is considered to be the central part of the pathogenesis of DN.Studies have shown that normal podocytes have a high level of autophagy,while a large number of experiments have shown that autophagy levels of podocytes in DN are down-regulated in vivo and in vitro.These results suggest that the inhibition of podocyte autophagy in DN may play an important role in the pathogenesis of podocytes,and tacrolimus has been found to restore the autophagy of cardiacmyocytes.Objective: In this study,the rat model of type 2 diabetes mellitus(T2DM)was established to investigate the effects of tacrolimus on podocyte injury and autophagy,and to further reveal the mechanism of autophagy in DN podocyte protection.Method: Forty healthy 8-week-old male wistar rats were randomly selected.Among them,10 rats were randomly selected as normal control group.The remaining 30 rats were fed with high sugar and high fat for 8 weeks.Then T2 DM model rats were established by intraperitoneal injection of small dose streptozotocin(STZ,30mg/kg).22 rats were successfully established into T2 DM,20 rats in good condition were randomly divided into diabetic mellitus group(DM group)and tacrolimus treatment group(FK506,0.5mg/kg d)for 8 weeks.The usual parameters were measured,including renal hypertrophy index(kidney weight/body weight,KW / BW),systolic blood pressure(SBP),fasting blood glucose(FBG),serum creatinine(Scr),total cholesterol(CH),serum triglycerides(TG),Alanine transaminase(ALT),Aspartate aminotransferase(AST),and white blood cell(WBC),urinary creatinine(UCr),urinary albumin(UAL).The creatinine clearance rate(Ccr)and urinary albumin excretion rate of 24 hours(UAE)were determined according to the formula.The changes of renal pathology and ultrastructure of podocyte were observed by the light and electron microscopy.The expression of nephrin and LC3-Ⅱ were determined by immunohistochemistry and Western-blot.Result: 1.22 of 30 rats were successfully established into T2 DM,and the successful rate was 73.33%.2.Compared with the NC group,KW/BW,SBP,FBG,TG,TC,UAE,Ccr of DM rats were significantly increased(P <0.05),and the KW/BW,UAE and Ccr were decreased in TAC group(P<0.05),while other parameters were no significant difference(P>0.05).3.Increased glomerular volume,mesangial cell proliferation,accumulation of mesangial matrix were shown by light microscope in DM group,but the above pathological changes were restored in TAC group.4.Under electron microscope,basement membrane thickening,the foot process became disorder and fusion in DM group,while these changes were significantly reduced in TAC group.5.Compared with the NC group,the expression of nephrin and LC3-Ⅱ were decreased in DM group(P<0.05),and both of parameters were restored after treatment of FK506(P<0.05).6.The Pearson correlation analysis showed that the renal LC3-Ⅱ/GADPH level was positively correlated with nephrin expression intensity(r=0.949,p<0.05).Conclusions: Tarcolimus can reduce proteinuria and podocyte damage of the rats with DN.The potential mechanism is that tarcolimus may enhance podocyte autophagy in type 2 diabetic model rats,leading to attenuate podocyte injury and delay progression of DN. |
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