| Objective:Diabetic nephropathy is the most common cause of end-stage of renal disease in the world. It is a serious hazard to human health. Diabetic nephropathy is characterized by glomerular hypertrophy, mesan-gial matrix expansion and glomerular basement membrane thickening followed by glomerulosclerosis; tubular basement membrane thickening and tubulointerstitial fibrosis. In recent years, protease-activated receptors family protein in role of renal diseases has been concerned. In this study, we investigated expression of Smad1 in kidney of diabetic nephropathy rat to explore the role of protease activated receptor-2 in tubulointerstitial fibrosis of diabetic nephropathy rats.Methods:60 Sprague-Dawley rats were randomly divided into three groups, control group included 15 rats, and diabetic group and treatment group were respectively 25 and 20 rats. Streptozotocin (55mg/kg) induced diabetics, rats receiving an injection of citrate buffer were used as controls. Treatment group rats were treated with the ARB, olmesarta (0.6mg/kg.d) after tow weeks, other rats treated with nomal saline. The rats were sacrificed at 2w,4w,8w,12w and 20w respectinely. Glycosylated hemoglobin, serum creatinine and kidney weight index were measured in each rats, while creatinine and albumin were measured from a 24-h urine collection, meanwhile kidney sections were observed by electron micros-copy, masson staining, periodic acid silver methenamine (PASM) and periodic acid Schiff (PAS) used to monitor the renal pathological changes. The protein expression of PAR-2 and collagen IV in kidney were detected by immunohistochemistry, the mRNA expression of PAR-2 was detected by reverse transcription polymerase chain reaction. Using an image analyzer with microscopy to analyse the correlation. Results:1. The levels of glycosylated hemoglobin, serum creatinine, kidney weight index,24h Albuminuria of diabetic rats were all progressive during the period of the experiment. The levels of HBAlc>24h urine volume and 24h albuminuria in diabetic group were remarkably higher than those in control group(p<0.05, p<0.01)meanwhile it showed that diabetic modal was successful.2. The results of immunohistochemistry showed that there is collagenâ…£expresses mesangial area, but in diabetic group were remarkably higher than those in control group, they were all progressive during the period of the experiment. Compared with treated group, Using Image-Pro PLUS analyzed that the levels of ColIV in kidneys of hyperglycemic rats were significantly increased (P<0.05).3. The results of immunohistochemistry showed that diabetic rats PAR-2 mainly expressed in the renal proximal convoluted tubule epithelial cells, with little expression in renal glomerular, decreased expression in the control group. Using Image-Pro PLUS analyzed that expression of PAR-2 significantly increased compared with control group (p<0.05), they were all progressive during the period of the experiment, and have a slight decline at 20w. But it was not statistically significance compared treated group. The results of reverse transcription polymerase chain reaction also show that expression of PAR-2 significantly increased compared with control group.4. Using Image-Pro PLUS analyzed that PAR-2 of diabetic rats was negative correlated with Ccr (r=-0.819, p<0.01), while 24h albuminuria showed a nicely association (r=0.908, p=0.043).Conclusions:PAR-2 mainly expressed in the renal proximal convoluted tubule epithelial cells in early diabetic rats, expression of PAR-2 in the diabetic rats show that PAR-2 may play a role in tubulointerstitial fibrosis of diabetic nephropathy. Angiotensin II type1 receptor blocker significantly ameliorates fibrosis of diabetic nephropathy, but it does not have relation with PAR-2 pathway.
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