凋亡相关基因Bax、Bcl-2及细胞色素C在链脲佐菌素糖尿病大鼠肾组织内的表达

Expressions of apoptosis - related gene Bax,Bcl-2 and cytochrome C in renal tissue of streptozotocin induced diabetic rats

目的观察糖尿病大鼠肾组织中促凋亡基因Bax、凋亡抑制基因Bcl-2及细胞色素C(cytochrome C,cytC)的表达变化。方法雄性SD大鼠24只,随机分为糖尿病组和正常对照组,每组12只。糖尿病组给予2%链脲佐菌素(溶于pH4.4、0.1 mol/L柠檬酸-柠檬酸钠缓冲液)按65 mg/kg单次腹腔注射,复制糖尿病模型。正常对照组只注射相当体积的枸橼酸缓冲液。分别于4周、12周后测体质量、尿蛋白、血糖、血清尿素氮及血清肌酐水平。用H-E染色观察肾形态学变化,免疫组织化学染色观察Bax、Bcl-2和cytC蛋白表达变化,TUNEL法观察大鼠肾皮质细胞凋亡情况。结果与正常对照组比较,糖尿病组大鼠24 h尿蛋白、血糖、尿素氮及血肌酐水平升高(P<0.05,P<0.01)。糖尿病组大鼠4周时肾小球体积增大,12周时肾小球系膜基质增生和肾小球硬化,肾小管上皮细胞空泡样变。随病程延长,糖尿病组大鼠肾小管上皮细胞Bax及cytC表达增加,而Bcl-2表达减弱。细胞凋亡检测结果显示,糖尿病组大鼠4周时凋亡细胞增多,多数在远曲肾小管,12周时远曲肾小管及近曲肾小管均可见凋亡细胞。结论Bax及cytC表达随糖尿病病程延长而增强,引起细胞凋亡增加,导致肾功能异常,这可能是糖尿病肾病的重要发病机制。

Objective To observe the changes in expressions of apoptosis-promoting gene Bax,apoptosis-inhibiting gene Bcl-2,and cytochrome C in the renal tissue of diabetic rats.Methods Twenty-four male Sprague-Dawley rats were randomly divided into 2 groups（n = 12） ： normal control group and diabetic group.Diabetic models were induced by single intraperitoneal injection of 2% streptozotocin（dissolved in pH 4.4,0.1 mol/L citric acid sodium buffer,65 mg/kg）.Normal control group was only injected with same volume of folic buffer.Animals were sacrificed at the 4 th and 12 th week,and body mass,24-hour urine protein,blood glucose,blood urine nitrogen and serum creatinine were determined.The changes of the renal morphology were observed by H-E staining.Immunohistochemical method was used to investigate the expressions of Bax,Bcl-2 and cytochrome C protein.The apoptosis of renal cortex cells was determined by TUNEL method.Results Compared with normal control group,the 24-hour urine protein,blood glucose,blood urine nitrogen and serum creatinine were significantly increased in the diabetic group（P〈0.05,P〈0.01）.The size of glomerulus was increased in diabetic rats during the 4 th week;hyperplasia of renal glomerulus mesangial matrix,glomerular sclerosis,and vacuolar degeneration in renal tubular epithelial cells were observed during the 12 th week.With disease progression in the diabetic group,the expressions of Bax and cytochrome C were increased and the expression of Bcl-2 was decreased.Apoptosis tests showed increased apoptotic cells in the 4 th week,mostly in both the distant tubular epithelial cells;in the 12 th week,apoptotic cells were seen in both the distant tubular and proximal tubules.Conclusion Renal expression of Bax and cytochrome C gradually increases with the progression of diabetes,inducing apoptosis of more cells and leading to renal dysfunction,which may partly contribute to the diabetic nephropathy in diabetic rats.