| Objective: Diabetic nephropathy is one of the most common forms of renal disease. Its pathological profile includes glomerulosclerosis, tubular atrophy and dilatation, and accumulation of extracellular matrix as well as interstitial fibrosis. As in other renal diseases, tubulointerstitial injury most closely correlates with progression of renal failure in diabetes. Mononuclear cell infiltration mediated in part by osteopontin (OPN) also figures prominently in this process. OPN has been characterized as a highly acidic, phosphoprotein. Recently a growing body of evidence indicates that osteopontin plays an important role in various models of renal diseases. OPN is a chemoattractant for macrophages and mononuclear cell and has a close relationship with macrophage infiltration, tubulointerstitium damage and decrement in renal function. In the other hands, it can promote proximal tubular cellular proliferation, remodelling and suppress tubular apoptosis. In addition, by inhibiting renal nitric oxide synthase, OPN plays both a pro-inflammatory and protective roles for renal function. AngiotensinⅡ(AngⅡ) can upregulate many cytokine and is closely involved in the pathogenesis of kidney diseases. The action of it could be inhibited by AngiotensinⅡreceptor 1 antagonosm(AT1RA).The role of AngⅡin regulatting OPN expression is arguable. The model of streptozotocin(STZ)-induced diabetes in Wistar rats was used to study the expression and location of OPN in the renal tissue and the relationship between OPN and macrophages as well as proliferation, in order to investigate the role of OPN in the process of diabetic nephropathy. In the same time, we used AT1RA (Losartan) to observe the influence of AngⅡon OPN expression. Methods: Experimental diabetes was induced in uninephrectomized Wistar rats by intraperitoneal injection of STZ (streptozotocin). The animals were divided into three groups: group A (control group), group B (diabetic group) and group C (Losartan-treated group). The rats of group B and C received a single intraperitoneal injection of STZ dissolved in 0.1mol/L sodium citrate (pH 4.5) at a dose of 65mg/kgWT. The rats of group A received an injection of the same volume of 0.1mol/L sodium citrate. The model of diabetes mellitus was considered to be successful when the blood glucose was ≥16.7mmol/L and the urine glucose was +++～++++ after 48～72 hours of the injection. The rats of group C received a gavage of Losartan at a dose of 40mg/kg per day for 56 days. The rats of group A and B received a gavage of the same volume of distilled water. Six rats for every group were respectively sacrificed at week 1, week 2, week 4 and week 8 after injection. Urine samples were collected before sacrificed and blood-serum samples were separated from femoral. The residual kidney was removed and prepared for lightmicroscopy, immunohistochemistry, western bloting and in situ hybridyzation. The expression of OPN, CD68 and PCNA proteins was evaluated by immunohistochemistry. OPN proteins were analysed also by western bloting. In situ hybridyzation was used to detect the mRNA expression of OPN. All the data were expressed as the form of x ±s. T test and F test were used to analyse the difference between the two groups and within one group. Statistical analysis was finished with SPSS software. Results: 1. Compared with group A of the corresponding period, the blood glucose, BUN and Urine protein of group B were higher, whereas the indexes of group C were greatly reduced. Ccr in group B was notably lower than group A. 2. Body weight of group B and C on 2 week were distinctly decreased. Kidney weight and the ratio of kidney/body weight were higher than group A. 3. The glomerular enlargement, mesangial expansion and vacuole in some tubular cells were observed in group B. The changes in group C were markedly ameliorated. 4. Immunohistochemically,only a few expression of OPN was observed in group A located to cortical tubular. Quantification of OPN immunostaining revealed a marked increase in group B and a further increase in group C. There was only a few Macrophage were scattered throughout the cortex in group A, At week 4, Macrophage accumulation was found in group B, and to take on a time-dependent upregulation. PCNA protein was expressed in nucleus.In group A, there was only few positive cells observed in tubules In group B, positive cells... |
PDF Full Text Request