| ObjectiveTo study the expression of SDF-1αand its receptor CXCR4 in the kidney of diabetic rats and study the relationship between vascular endothelial growth factor (VEGF) and SDF-1αand its receptor CXCR4 in diabetic nephropathy, and the effects of irbesartan on SDF-1αand its receptor CXCR4, VEGF; To provide a new theoretical basis for the clinical treatment of diabetic nephropathy and delay of its development.Methods48 healthy male Wistar rats which weight were 180-200g were randomly divided into normal group (A), diabetic control group (B) and diabetic treatment group (C) and every group have 16 rats. All rats were anesthetized and underwent right renal resection after feeding a week. The rats of B, C group were given intraperitoneal injection of a single dose of STZ (streptozotocin, STZ)60mg/kg, the rats of A group were given the same dose of citrate buffer after two weeks. Detect the blood glucose of tail vein at least consecutive 3 d after 72 h. If the concentration of blood glucose were≧ 16.7 mmol/L with continuous 3 times, the model was seen as a successful diabetes model. Diabetes treatment group (C) wer given irbesartan 25mg/kg.d by intragastric administration to the end of the experiment since the model was founded successfully;diabetic control group (B)and normal group (A) were given the same dose of saline. Fasting blood glucose, glycosylated hemoglobin,24h urinary albumin excretion rate (UAER) (RIA), blood lipid,glycated hemoglobin,serum creatinine, blood urea nitrogen and creatinine clearance rate of diabetic rats were measured in 4 weeks,8 weeks,16 weeks;the results of the same period of the three groups were compared;the correlation among the indexes were analyzed. All rats were killed in the 16th weekend and we took kidney tissue samples, stripped capsule, weighed, measured kidney weight/ body weight ratio,and calculated index of kidney hypertrophy (KW/BW). A portion of kidney tissue were put into 10% formalin solution and paraffin section line,for HE and PAS staining; The changes of pathological of renal were observed with HE and PAS staining,mean glomerular volume (MGV) and mesangial area ratio (FMA) were analyzed with medical image analysis system; and we detected the SDF-la and its receptor CXCR4, VEGF by immunohistochemical method and annlyzed their linear correlation.Results(1) survival of rats:normal control group (A group) all survived; diabetic control group (B group) respectively died one because of infection on 75,80,93,105 days; diabetes treatment group (C group) respectively died one because of a high blood sugar on 95,108 days.(2) General conditions:the rats of normal control group (A group) were in good condition, coat gloss, responsive, and weight gain. The rats of diabetic control group (B group) had more to drink, polyuria, polyphagia, weight loss of the typical "more than three a little" symptom, yellow fur, subcutaneous abscess and moved slowly. One rat appeared cataract, one rat had repeated diarrhea, four rats died of infection. Compared with the rats of B group,2 rats of C group died of high blood sugar, the remaining rats:the symptoms of "more than three a little" reduced, more glossy coat, weight increased. Our research show irbesartan control the symptoms of DM to some extent.(3) blood glucose, glycosylated hemoglobin, blood lipid:in the first 16 weeks, compared with the A group, blood glucose and glycated hemoglobin of the diabetic control group (B group) and treatment group (C group) were significantly higher (P<0.05); while the blood glucose and glycated hemoglobin of B and C group were not significantly different (P> 0.05).(4) other biochemical parameters:①UAER:compared with the A group, UAER of B group significantly increased in the first 8 weeks; UAER remained persistently increase in the first 16 weeks and increased significantly than the first 8 weeks.Compared with the B group, UAER of C group in the same period decreased (P<0.05).②Scr:Scr of the B group was significantly higher than the A group (P<0.05), compared with B group, Scr of C group decreased significantly (P<0.05), the level of Scr of C group and A group were similar (P <0.05).③Ccr:compared with A group, the Ccr of B group had begun to decrease (P<0.05),C group was more obvious but still higher than A group (P <0.05) in the first 16 weeks.(5) Renal weight, renal hypertrophy index (KW/BW), mesangial area ratio (FMA) and mean glomerular volume (MGV) were measured in the first 16 weeks.Compared with A group, KW/BW, MGV and FMA of rats of B group significantly increased (P<0.05). Compared with the B group, KW/BW, MGV and FMA of C group decreased(P<0.05) but still higher than the A group (P <0.05).(6)The pathological changes of renal under electron microscopy in the first 16 weeks (glomerular sclerosis, interstitial fibrosis, tubular atrophy, vascular intimal lesions):B group and C group:glomerular capillary basement membrane thicken, department of membrane of the interstitial and mesangial cell proliferation significantly; but C group was significantly reduced (P<0.05) than B group in the same period, and compared B, C groups with A group, the difference was significant (P<0.01).(7) Expression of SDF-la, CXCR4 and VEGF of renal tissue in immunohistochemistry:the SDF-1α, CXCR4, and VEGF were weakly positive in normal control group (A group), while SDF-1α, CXCR4 and VEGF in the cytoplasm of renal tubular epithelial cells and glomerular parietal epithelial cells increased in the diabetic groups (B, C group), and they were more obvious in inflammatory infiltration and interstitial fibrosis; and expression of SDF-1α, CXCR4 and VEGF were significantly higher than the normal group, the rendering of three cytokines increased with the duration of the injuries. In the first 16 weeks, Overall SDF-1α, CXCR4 and VEGF of renal tissue of B group were significantly higher than A group, the difference was significant (P<0.01); compared with C group and B group, overall significantly lower (P<0.01); compared with B group, SDF-1α, CXCR4 and VEGF of C group were inhibited and decreased significantly (P< 0.01).Conclusion1.SDF-1α, CXCR4, and VEGF were highly expressed in the tissue of kidney of diabetic rats; SDF-1α, CXCR4, and VEGF may be associated with the occurrence of diabetic nephropathy development.2.SDF-1αbinding to CXCR4-mediated upregulation of VEGF is one of important mechanism of diabetic nephropathy. 3. Irbesartan can inhibit the SDF-1α; CXCR4 and VEGF, and thus it has a protective effect on diabetic nephropathy and delay the development of diabetic nephropathy. |
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