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目的研究雷帕霉素对糖尿病大鼠早期肾脏病变的影响,探讨血管内皮生长因子(VEGF)在糖尿病肾病发病中的作用。方法SD大鼠经链脲佐菌素(STZ,65mg/kg)一次性腹腔注射建立糖尿病模型。建模成功后分为雷帕霉素治疗组(建模后12周开始用雷帕霉素治疗4周,n=9)、血管紧张素Ⅱ(ATⅡ)受体拮抗剂L-158809治疗组(阳性对照组,建模后12周开始用L-158809治疗4周,n=5)和糖尿病肾病组(建模12周后用等量蒸馏水灌胃4周,n=9),以未建模SD大鼠作为正常对照组(n=9)。采集各组大鼠血、尿样本和肾脏组织标本,观察和分析各组大鼠肾小球结构和功能的改变;Western blotting和免疫组织化学法检测肾脏组织VEGF及其受体VEGFR2的表达。结果与正常对照组比较,糖尿病肾病组大鼠24h尿白蛋白增加、内生肌酐清除率升高、肾小球体积增大、肾小球基膜增厚,两组间比较差异均有统计学意义(P<0.01)。与糖尿病肾病组比较,雷帕霉素治疗组和阳性对照组大鼠24h尿白蛋白较少,且肾小球体积增大和基膜增厚均不明显。大鼠肾脏组织VEGF和VEGFR2表达,糖尿病肾病组明显高于正常对照组(P<0.01),雷帕霉素治疗组和阳性对照组显著低于糖尿病肾病组(P<0.01)。结论雷帕霉素具有减少糖尿病肾病大鼠蛋白尿和缓解肾小球肥大和基膜增厚的作用。抑制肾脏组织VEGF和VEGFR2蛋白表达可能是雷帕霉素延缓糖尿病肾病发病的可能机制之一。
Objective To investigate the effect of rapamycin on early diabetic nephropathy in diabetic rats and to explore the role of vascular endothelial growth factor (VEGF) in the pathogenesis of diabetic nephropathy. Methods Diabetic rats were induced by intraperitoneal injection of streptozotocin (STZ, 65mg / kg). After successful modeling, the rats were divided into rapamycin treatment group (n = 9 for 12 weeks after model initiation, rapamycin treatment, n = 9), and angiotensin II receptor antagonist L-158809 Positive control group, L-158809 for 4 weeks, n = 5) and diabetic nephropathy group (12 weeks after modeling, the rats were treated with equal volume of distilled water for 4 weeks, n = 9) SD rats served as normal control group (n = 9). Blood samples, urine samples and kidney tissue samples from each group were collected to observe and analyze the changes of glomerular structure and function in each group. The expressions of VEGF and VEGFR2 in kidney tissues were detected by Western blotting and immunohistochemistry. Results Compared with the normal control group, the urinary albumin increased, the creatinine clearance rate increased, the glomerular volume increased, the glomerular basement membrane thickening in the diabetic nephropathy group, the differences between the two groups were statistically significant Significance (P <0.01). Compared with the diabetic nephropathy group, 24h urinary albumin was less in the rapamycin-treated group and the positive control group, and the glomerular volume was increased and the basement membrane thickening was not obvious. The expression of VEGF and VEGFR2 in rat kidney tissue was significantly higher in diabetic nephropathy group than that in normal control group (P <0.01). The levels in rapamycin group and positive control group were significantly lower than those in diabetic nephropathy group (P <0.01). Conclusion Rapamycin can reduce the proteinuria and relieve the glomerular hypertrophy and basement membrane thickening in rats with diabetic nephropathy. Inhibition of renal tissue VEGF and VEGFR2 protein expression may be rapamycin delay the pathogenesis of diabetic nephropathy may be one of the mechanisms.