雷帕霉素对糖尿病肾病大鼠足细胞损伤的作用

Effects of rapamycin on podocytes of rats with diabetic nephropathy

目的观察哺乳动物雷帕霉素靶分子(mTOR)信号抑制剂雷帕霉素对糖尿病肾病大鼠足细胞的作用。方法 SD大鼠经链脲佐菌素(STZ)一次性腹腔注射建立糖尿病模型。建模成功后,将糖尿病SD大鼠随机分为雷帕霉素治疗组(建模后第12周开始用雷帕霉素治疗4周,n=6)、糖尿病肾病组(建模后第12周开始用等量生理盐水灌胃4周,n=6),以未建模SD大鼠作为正常对照组(n=6)。BCA法检测各组大鼠24 h尿总蛋白水平;光学显微镜下观察大鼠肾脏组织学改变,透射电子显微镜观察足细胞足突形态并测量足突宽度;采用免疫荧光染色激光共聚焦显微镜及Western blotting法检测足细胞损伤标志蛋白desmin和足细胞标志蛋白podocin的表达。结果与糖尿病肾病组比较,雷帕霉素治疗组大鼠24 h尿总蛋白排泄量显著减少(P<0.05);肾小球系膜基质积聚缓解,炎症细胞浸润轻微,肾小球体积小且足细胞宽度窄(P<0.05);足细胞desmin表达减少,podocin表达增加。结论雷帕霉素可减轻糖尿病肾病大鼠的蛋白尿症状,这可能与雷帕霉素对足细胞的保护作用有关。

Objective To investigate the effects of rapamycin on podocytes of rats with diabetic nephropathy. Methods Diabetic SD rat models were established by intraperitoneal injection of streptozotocin （STZ）. After model establishment, diabetic SD rats were randomly divided into rapamycin treatment group （rapamycin treatment for 4 weeks since the twelfth week after model establishment, n = 6） and diabetic nephropathy group （intragastric administration of the same amount of normal saline for 4 weeks since the twelfth week after model establishment, n = 6）, and 6 SD rats without model establishment were served as normal control group. Twenty-four h urinary protein excretion was determined by BCA protein assay. The histological changes of kidney were observed by light microscopy, and the foot processes effacement and width of foot processes were determined with electron microscopy. Laser confocal microscopy with immunofluoreseence staining and Western blotting were employed to detect the expression of desmin and podocin. Results Compared with diabetic nephropathy group, the 24 h urinary protein excretion in rapamycin treatment group was significantly reduced （P 〈 0.05）. The glomerular pathological changes were alleviated by rapamyein treatment. The width of foot processes was shorter in rapamycin group than in diabetic nephropathy group （P 〈 0.05）. There was lower expression of desmin and higher expression of podocin in podocytes in rapamycin treatment group. Conclusion Rapamycin may attenuate the urinary protein in rats with diabetic nephropathy, which may be associated with the protection of podocytes by rapamycin.