| Objective: Diabetes mellitus (DM) is a life-long chronic disease and its incidence is increasing year by year. It's severely threatening the human's health. Diabetic nephropathy (DN) is one of the commonest microangiopathies of type 2 diabetes mellitus and is a major cause of end-stage renal failure (ESRF). Basement-membrane thickening and mesangial expansion have long been recognized as pathological hallmark of DN. The pathogenesis of this fibrotic process has not been clarified completely yet. It involves several mechanisms, among which the inhibition of extracellular matrix (ECM) degradation appears to play an important role. As a key enzyme of the ECM proteolysis systems, the matrix metalloproteinase system (MMPs) can degrade nearly all the matrix components. It may play a key role in the occurrence and development of DN. Type IV collagen(Col-Ⅳ) is the main component of the normal glomerular basement membrane and MMP-9 is one of the main enzymes which degradate Col-Ⅳ. Most studies suggested that the expression and activity of MMP-9 in kidney was downregulated in DN. But there were some different ideas and the mechanism of MMP-9 in the pathogenesis of DN needs further study. Panax notoginseng (Pn) and Astragalus mem-branaceus (Ast) are the common traditional Chinese medicines, which could prevent and cure diabetes and its complications. In this study type 2 diabetic rat model was established by high-fat diet and intraperitoneal injection of streptozocin (STZ). The characteristics of this model were similar to that of human type 2 DM. The expression and activity of MMP-9 in the rat kidney and the the expression of Col-Ⅳwere detected in order to discuss their roles in the pathogenic mechanics of DN. At the same time, Pn and Ast were applied to investigate their preventive and treatment mechanisms of DN. Methods: Female SD rats were divided into 2 groups randomly: normal control rats (group A) and test rats. The normal control rats were fed with routine diet and the test rats were fed with high-fat diet. After a month insulin resistance was induced. Then STZ (30mg/kg) was injected intraperitoneally to destroy some pancreas in order to induce hyperglycemia. Six weeks later, the rats whose blood glucose level was higher than 7.8mmol/L and insulin sensitivity decreased were considered as diabetes. The diabetic rats were randomly divided into following groups: diabetic model rats (group B), diabetic model rats treated with Pn (group C), and diabetic rats treated with Pn and Ast (group D). After 4 weeks and 6 weeks of the experiment, body weight, blood glucose, insulin and lipids were measured. After 18 weeks of the experiment, urinary albumin, BUN, Scr, Ccr, blood glucose, serum triglyceride (TG), serum totalcholesterol (TC), very low density lipoprotein cholesterol (VLDL-C), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C) were detected. Morphological changes were observed by microscope. The expression and activity of MMP-9 in rat kidney were detected by immunohistochemistry and zymography respectively. The expression of Col-Ⅳwas measured by immunohistochemistry. Results were analyzed by computer image-analysis system and the IOD of MMP-9 and Col-Ⅳin the rat kidney tissue were counted. Results 1 At the end of 4 weeks, the test rats were heavier than group A (P<0.05). The blood glucose, insulin, TG and TC of test rats were significantly higher than those of control rats (all P<0.01). At the same time, the insulin sensitive index (ISI) in test groups was lower than that of control rats (P<0.01). 2 Six weeks after experiment, the insulin concentrations of test rats were decreased to the level of control rats. Other features were retained. In test group, blood glucose had exceeded 7.8mmol/L and the ISI was significantly lower than that in control rats. 3 When the experiment was finished, blood glucose of group B was significantly higher than that of group A (P<0.01), and blood glucose of group C and D was significantly lower than that of group B (all P<0.01). TG, TC, LDL-C and VLDL-C of group B were significantly higher than those of group A (allP<0.01). In group C and D, all these indexes decreased obviously compared with those in group B.HDL-C in group B was decreased (P<0.01), but increased in group C and D (both P<0.01). Alb, BUN and Scr of group B were significantly higher than that of control groups (all p<0.01). But Ccr was much lower. 4 The morphological examination: In group B, there were a slight mesangial cell proliferation and ECM deposition in mesangial regions. The glomerular basement membrane (GBM) was thickened and the PAS-positive material deposited in the mesangium. The area of glomerulus was increased. All the changes were attenuated in group C and D. 5 The protein expression of MMP-9 and Col-IV in renal cortex: The IOD of MMP-9 in group B was significantly lower than that of group A (P<0.01). It was elevated in group C and D (both P<0.01). In group B, the protein expression of Col-Ⅳ(13.02±1.74)was much higher than that of the control group (6.27±0.72).The IOD of Col-Ⅳin group C and D were much lower than that in group B(both p<0.01).The Col-Ⅳof group D (9.02±1.20) was lower than that of group C (10.24±1.32) (p<0.01).Correlation analysis showed that the expression of MMP-9 had negative correlation with Col-Ⅳ(r=-0.589,p< 0.01). 6 The bioactivity of MMP-9 in renal cortex: the bioactivity of MMP-9 in group B(833.18 ±57.78) was significantly lower than that of group A(1770.00±109.14)...
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