| Background and objective Chronic kidney disease (CKD) finally develop into Renal fibrosis and it is the common pathway of kidney diseases running to end-stage renal disease (ESRD) ,but unfortunately the intimate mechanisms leading to the development and progression of renal injury are not yet fully known. The recent study evidences demonstrated that podocyte injury play a major role in the development and progression of renal fibrosis,and that to protect podocyte from damage can effectively retard the progress of renal fibrosis. PAP is a new, potent immunosuppressive agent,it possesses a variety of pharmacological functions, including anti-inflammation, anti-virus,anti-proliferation and protecting vascular. Some research has shown that PAP has significant protective effects on focal segmental glomerulosclerosis.RLX is a selective estrogen receptor modulator, many studies indicate that treatment with RLX ameliorated albuminuria, mesangial expansion, and accumulation of extracellular matrix.The purpose of the present study was to dynamically observe numuber of podocytes in Adriamycin-induced nephropathy by investigate the expression of WT-1,and to explore the role of podocytes in development of proteinuria and chronic renal fibrosis. Forthermore we investigate the effects of above two drugs on number of podocyte in Adriamycin-induced nephropathy and explore the possible mechanism.Methods Seventy-six male Sprague-Dawley rats were separated into four groups at random. Control group (group A, n=16), model group (group B,n=20), model group treated with RAP1.5mg·kg?1 (groupC, n=8), model group treated with RXL 3.0 mg·kg?1 (group D,n=32). Adriamycin-induced nephropathy was induced by tail intravenous injection of Adriamycin for two times. RPA and RXL were given by gavage every day after 2 tweeks of injecting aclarubicin for the first time.Samples of group A ,group B and group D were collected at the end of 4th,7th,10th and 13th week respectively. Samples of group A. At the end of 7th week, samples of group C were collected. The renal histology was observed with light microscope and electronic microscope, the amount of proteinuria was measured with BCA protein assay kit. Both immunohistochemistry method and Western blot analysis. werw used to detect the level of WT-1. Expression of TGF-β1 was measured by immunohistochemistry method.Results 1. 24h Urinary protein excretion: At the end of 4 th,7th,10th,13th week,24h Urinary protein excretion were siginificantly increase in groups B,C and D compared with group A (P<0.01) and they rose further as the disease-process progressed(P<0.01). 24h Urinary protein excretion in group C and D were decreased significantly compared with those in group B in crossponding time (P<0.01).2. Renal pathologic morphology:Lightscope observation showed that focal segmental glomerulosclerosis, glomeruli hypertrophy,Bowman's capsule expansion and focal fibrosis in renal tubulointerstitium were found in group B at the end of 7th week. At the end of 13th week glomeruloselerosis and tubulointerstitial fibrosis were extensive. TEM observation showed that extensive podocyte foot process fusion, fracture disappeared and a large number of organelle and small vacuoles in the cytoplasm. At the end of 10th ,we can see podocye detached from the GBM and GBM thickening apparently. With the development of disease-process ,lesions were obviously aggravated and ameliorated in group C and D.3. WT-1 protein expression in renal tissue: Both Western blot analysis and immunohistohemistrical staining method noted that the expression of WT-1 was decreased at the end of 4th week in group B. The protein level of WT-1 in group B was reduced by24%,42%,56% and 70% respectively as low as those in the group A. The protein level of WT-1 in group C and D were increased significantly compared with those in group B in crossponding time (P<0.01).4. TGF-β1 protein expression in renal tissue: There was minimal immunohisto- hemistrical staining for TGF-β1 in renal glomerulus of group A rats. It was markedly increased in group B,C and D(P<0.01). Compared with those in group B, expression of TGF-β1 protein were significantly inhibited in group C and D in crossponding time (P<0.01).Conclusion A relative decrease of the density and an absolute decrease in the numuber of podocytes was positively correlated with the amount of proteinuria, maybe play a key role in the development of chronic renal fibrosis.Both RAP and RXL can decrease the loss of podocyte, whose mechanism may be at least partly correlated with up-regulating the expression of TGF-β1 in the kidney.
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