SREBP-1在1型糖尿病大鼠肾脏的表达和胰岛素的干预性研究

目的探讨1型糖尿病大鼠肾脏脂质沉积和固醇调节元件结合蛋白-1(sterol regulatory element binding protein-1,SREBP-1)的表达以及胰岛素处理的影响。方法以Wistar大鼠建立链脲佐菌素1型糖尿病模型并随机分为正常对照组,糖尿病模型组和胰岛素处理组。喂养2 wk后处死,测定肾皮质组织甘油三酯含量,油红O染色检测脂质沉积的部位;免疫组织化学、Western blot和原位杂交检测肾脏SREBP-1表达。结果与正常对照组相比,1型糖尿病大鼠肾脏甘油三酯含量明显升高,油红O检测示脂质沉积定位于肾近曲小管上皮细胞,肾小球内未见着色。胰岛素处理明显降低了甘油三酯含量,和糖尿病模型组相比差异有统计学意义。免疫组织化学检测SREBP-1定位于大鼠肾脏近曲小管上皮细胞胞质,糖尿病组表达量明显高于正常组和胰岛素处理组。Western blot证实了SREBP-1蛋白前体片段和成熟片段在糖尿病组的高表达,前体片段积分光密度比值为0.673±0.027,成熟片段为0.670±0.028,分别是正常组的1.86倍和1.77倍;胰岛素处理后SREBP-1蛋白前体片段表达下降了52.8%,成熟片段表达量下降了30.9%。原位杂交结果证实SREBP-1 mRNA定位于近曲小管上皮细胞胞质,糖尿病组表达明显升高,与正常对照组相比差异有统计学意义(P<0.01);胰岛素处理后其表达明显下降。结论1型糖尿病大鼠肾近曲小管上皮细胞SREBP-1 mRNA和蛋白表达升高可能参与了肾脏脂质沉积,胰岛素处理可有效降低SREBP-1mRNA和蛋白表达。

hebmu.edu.cnExpression of SREBP-1 in kidney of type 1 diabetic rats and insulin intervention

Aim To investigate the expression of SREBP-1(sterol regulatory element binding protein-1) in the kidney of type 1 diabetic rats and the effect of insulin.Methods The type 1 diabetic models were induced by high dose of STZ and rats were randomly divided into three groups: normal control group,diabetes control group and insulin treated group.At the 2nd week end,the triglyceride(TG) content in the kidney of experimental rats was measured by the assay kit and oil Red O staining.Furthermore,the expression of SREBP-1 protein was detected by the methods of Western blot and immunohistochemistry.The analysis of SREBP-1 mRNA was performed by in situ hybridization.Results Compared with the control group,the type 1 diabetic rats' renal triglyceride content markedly increased,and the result of Oil Red O showed that lipid deposited in the renal tubular epithelium.Triglyceride content markedly decreased after insulin treatment.The difference had statistic meaning,compared with the diabetes model group.Immunohistochemistry presented the results that SREBP-1 protein was up-regulated in renal tubular epithelium of diabetic rats and insulin treatment suppressed the increasing.The results of western blot showed that the precursor and mature segments of SREBP-1 protein in kidney of diabetes group rats were about 1.86 times and 1.77 times respectively of that of normal control group rats.In situ hybridization confirmed the increasing of SREBP-1 mRNA in renal tubular epithelium in diabetic rats.The effect of insulin treatment on SREBP-1 expression was detected by the methods of Western blot and in situ hybridization and it was found that the SREBP-1 mRNA and protein of kidney were down-regulated.Compared with the normal group,the difference has statistic meaning(P<0.01);the expression decreased markedly after the insulin treatment.Conclusion The above results suggests that altered SREBP-1 may play an important role in the pathogenesis of renal lipid accumulation in type 1 diabetic rats and insulin treatment can suppress the alteration.