The Effects Of GSk3β Inhibitor On The Expression Of Renal TGF-β1and Serum PAI-1of Diabetic Nephropathy In Rats

Background：Glycogen synthase kinase-3beta (glycogen synthase kinase-3Beta,GSK-3Beta) is aserine/threonine kinase,which involved in a number of cell signalling pathways, playing animportant role in glycogen metabolism,cell differentiation and proliferation and geneexpression.We found the abnormal elevation of GSK-3β activity in the liver and muscletissue in type2diabetes mellitus.GSK-3β weaken insulin signal transduction,thus inhibitglucose utilization and glycogen synthesis,and that lead to insulin resistance.The etiology oftype2diabetes mellitus is insulin resistance,therefore,GSK-3β inhibitors which can be usedto treat type2diabetes mellitus can alleviate insulin resistance.DiabeticNephropathy(Diabetic Nephropathy,DN) is one of the most serious complications ofdiabetes.Glomerular basement membrane thickening,extracellular matrix(extracellularmatrix,ECM) accumulation,tubular atrophy and interstitial fibrosis are the main pathologicalmanifestations of DN.Foreign studies have shown that GSK-3β inhibitor LiCl can increasethe expression of Akt and GSK-3β phosphorylation levels and nuclear beta-catenin,thusreduce high glucose-induced glomerular mesangial cells apoptosis and proteinuria of DNrats.In recent years a growing number of studies have shown that the severity of diabetictubulointerstitial lesions are closely related to renal function decline.However,therelationship between GSK-3β activity and diabetic tubulointerstitial lesions,the effects ofGSk-3β inhibitor on diabetic nephropathy and its mechanism are not well defined.Objective:This experiment eatablished a rat model of diabetic nephropathy,then gave GSk-3βinhibitor Licl for drug intervention.The study would investigate the influence of Licl onproteinuria,blood glucose,serum creatinine,renal pathological,TGF-β1expression in renaltissues and serum PAI-1,so as to estimate the the effect of GSk-3β inhibitor on diabeticnephropathy and its mechanism.Methods:60male Wistar rats were randomly divided into four groups:Normal control group(NCgroup,n=10),Licl group(n=10),DN group(n=20),DN+Licl group(n=20).The rat model ofdiabetic nephropathy was established by single intraperitoneal injecting STZ and feedinghigh fat diet.Drug intervention was implemented by intraperitoneal injecting GSk-3βinhibitor Licl.The study observed the changes in general state,weight,kidney weight/body weight of rats in each group;It also detect indexes such as blood glucose,urinevolume,urinary protein,serum creatinine and renal pathological changes by PAS stainingmethod.The study detected serum PAI-1by enzyme-linked immunosorbent assay(ELISA)and TGF-β1expression in renal tissues by immunohistochemisty(IHC),then carriedout group comparison.Results:Compared with normal control group,general state,weight,kidney weight/bodyweight,blood glucose, serum creatinine,urine volume,urinary protein of DN group ratsappeared specific features of DN,serum PAI-1increased significantly(P＜0.05),TGF-β1expression in renal tissues was upregulated significantly (P＜0.05).The renal pathologyresults showed that:normal control group showed normal pathology,the kidney of DN ratsshowed increased glomerular volume,diffuse mesangial area widened,extracellular matrixdiffuse increased,part of the visible capillary basement membrane thickened, diffuse granulardegeneration and focal vacuolar degeneration of renal tubular epithelial cell,protein castscould be seen in the small tubes,focal inflammatory cell infiltration of renalinterstitial.Compared with DN group,survival rate of DN+Licl group was higher;urinaryprotein,serum PAI-1decreased strikingly（P＜0.05）;TGF-β1expression in renal tissuesincreased sharply（P＜0.05）;While,blood glucose,weight,kidney weight/body weight ofDN+Licl group were not significantly different(P>0.05);The renal pathology of this groupwas alleviated notably,widened mesangial area and increased matrix tended to getbetter,protein casts in renal tubules decreased sharply, inflammatory cell infiltration of renalinterstitial ameliorated. Compared with normal control group,general state,weight,kidneyweight/body weight,blood glucose,urine volume,urinary protein,serum creatinine,renalpathological changes,serum PAI-1,TGF-β1expression in renal tissues of Licl group were notsignificantly different (P>0.05).Conclusion:1.GSK-3β inhibitor lithium chloride can reduce proteinuria and mortality rate ofdiabetic nephropathy rats.2. Compared to normal rat, serum PAI-1level of diabetic nephropathy rats wassignificantly increased.GSK-3β inhibitor lithium chloride can reduce serum PAI-1level ofdiabetic nephropathy rats,thus reduce the excessive accumulation of renal ECM mediated byPAI-1, ease coagulation and fibrinolysis disorders.3. Compared to normal rat, TGF-β1expression in renal tissues of diabetic nephropathy rats was significantly up-regulated. GSK-3β inhibitor lithium chloride can increase TGF-β1expression in renal tissues of diabetic nephropathy rats,thus increase renal tubular EMT andrenal interstitial fibrosis mediated by TGF-β1.4. Inhibition of GSK-3β have a positive significance in treatment of diabeticnephropathy. However, GSK-3β inhibitor lithium chloride using as drug treatment ofdiabetic nephropathy, the two sides of its effects should be considered.