α-酮酸配伍低蛋白饮食对糖尿病大鼠肾脏肥大的影响及其与肾小球周期素激酶抑制剂p27的关系

Experiment on effects of low-protein diet supplemented with α-ketoacids on hypertrophy of diabetic glomerulus and its relationship with the level of cyclin kinase inhibitor p27

目的 探讨α 酮酸配伍低蛋白饮食对糖尿病大鼠肾脏肥大的影响及其与肾小球周期素激酶抑制剂 p2 7的关系。 方法 腹腔注射链脲佐菌素建立糖尿病 (DM )模型 ,分别予正常蛋白 (蛋白占饲料重量的 10 % ,NPD组 )、低蛋白 (蛋白占饲料重量的 5 % ,LPD组 )、α 酮酸 +低蛋白 (蛋白占饲料重量的 5 % ,其中α 酮酸提供1%的蛋白 ,LPD +α KA组 )饮食治疗 8周。蛋白印迹 (Western杂交 )方法测定肾小球裂解液p2 7蛋白水平 ,ELISA方法测定肾小球裂解液细胞外基质 (ECM )蛋白 (Ⅳ型胶原及纤维连接蛋白 )和尿白蛋白 ,采用图像分析系统测定肾小球面积。结果 各组DM大鼠肾小球 p2 7水平及ECM蛋白水平均增高 ,尿白蛋白排泄增多 ,肾重 /体重比例增高 ,肾小球面积增大 ,但LPD组及LPD +α KA组大鼠的变化较NPD组轻。LPD +α KA组肾小球p2 7水平 (8.6± 2 .3)较LPD组 (11.1± 3.6 )显著降低 (P <0 .0 1) ,ECM蛋白水平进一步下降 ,尿白蛋白排泄减少更明显 (P <0 .0 1) ,DM大鼠肾重 /体重比例下降更显著 (P <0 .0 5 ) ,肾小球面积进一步减少 (P <0 .0 5 )。DM大鼠肾小球 p2 7水平与肾重 /体重比例呈直线相关。LPD组、LPD +α KA组和NPD组间的血糖水平及血白蛋白水平差异无显著性。结论 α 酮酸配伍低蛋白饮食可能通过降低肾?

Objective To investigate the relationship between the cyclin kinase inhibitor p27 and the effect of low protein diet supplemented with α keto acids on hypertrophy of diabetic glomerulus in rats. Methods STZ induced diabetic rats were given low protein diet (5%protein in fodder)or low protein diet supplemented with α keto acids (5%protein in fodder including 1% protein supplied by α keto acids ) or normal protein diet(10%protein in fodder )for 8 weeks. The p27 protein of glomerular lysate was detected with Western Blot. The extracellular matrix (ECM) protein (type Ⅳ collagen and fibronectin) of glomerular lysate and 24 h urine albumin were examined with ELISA. Image analysis system was used to detect the diameter of each glomerulus. Results Glomerular p27 protein increased in diabetic rats no matter what kinds of diet were given. Meanwhile, the 24 h urine albumin , glomerular ECM, glomerular diameter elevated as well as the ratio of kidney weight over body weight in diabetic rats. Both low protein diet and low protein diet supplemented with α keto acids could attenuate changes occurred in diabetic rats with normal protein diet. Glomerular p27 level(8.6±2.3 vs 11.1±3.6, P <0.01),24 h urine albumin, (13.21±2.49 ) μg/24 h vs (18.13±3.23 )μg/24 h, P <0.01,glomerular diameter,(652±73)μm 2 vs (721±75)μm 2, P <0.05, and the ratio of kidney weight over body weight(11.02±1.72 vs 12.03±1.85, P <0.05) were lower in diabetic rats with low protein diet supplemented with α keto acids than diabetic rats with low protein diet. Solely glomerular p27 level was linearly related with the ratio of kidney weight over body weight in diabetic rats. The blood glucose and serum albumin remained constant in diabetic rats no matter what kinds of diet were given. Conclusion Low protein diet supplemented with α keto acids can further inhibit glomerular hypertrophy,and may protect diabetic glomerulus through decrease of glomerular p27 level.