控制血糖对糖尿病大鼠肾PTEN表达及纤维化病变的影响

目的:观察控制血糖前后糖尿病(DM)大鼠肾组织第10号染色体缺失的磷酸酶和张力蛋白同源基因(PTEN)表达变化,探讨PTEN与肾小管上皮细胞向间充质细胞的转化(EMT)的关系及控制血糖对PTEN表达及肾纤维化病变的影响。方法:SD大鼠随机分为正常对照组(N)、糖尿病组(DM)、胰岛素治疗组(DMA),尾静脉注射STZ复制DM模型,于成模13周起,DMA组大鼠采用胰岛素个体化治疗,以血糖控制在4～7 mmol/L,尿糖阴性为准,分别于16周和24周时处死各组大鼠。生化方法测血糖、血肌酐和24 h尿蛋白;观察肾脏病理改变;免疫组织化学和Western blotting检测各组大鼠肾组织PTEN、CollagenⅣ、FN、E-cadherin和α-SMA蛋白的表达;RT-PCR检测PTENmRNA的表达。结果:与N组相比,不同时间点DM组大鼠血糖、血肌酐、24 h尿蛋白明显增多(P<0.05),并出现肾组织纤维化改变;而DMA组大鼠血糖、血肌酐、24 h尿蛋白均显著低于DM组(P<0.05),肾纤维化病变明显改善;不同时间点的DM组大鼠肾组织PTEN蛋白和mRNA的表达均较N组明显减少(P<0.05),并伴有E-cadherin的表达减少(P<0.05),α-SMA表达增加(P<0.05),CollagenⅣ和FN蛋白的沉积增多(P<0.05);而与DM组相比,DMA组大鼠肾组织PTEN蛋白和mRNA表达均明显增加(P<0.05),且E-cadherin的表达增加(P<0.05),α-SMA表达减少(P<0.05),CollagenⅣ和FN在间质的沉积减少(P<0.05)。结论:控制血糖能上调肾小管上皮细胞PTEN的表达,同时能减少肾小管上皮细胞EMT及肾间质ECM沉积,改善肾纤维化病变。

Effects of Blood Glucose Control on Expression of PTEN and Fibrotic Lesions in Renal Tissue of Diabetic Rats

Objective: To explore the influence of blood glucose control on renal PTEN expression and renal fibrosis in diabetic rats.Methods: SD rats were randomly divided into control(N),diabetes mellitus(DM) and insulin-treated DM groups(DMA).DM model was established by tail intravenous injection of streptozotocin(STZ).Since the 13th week of successful modeling,rats in group DMA were given insulin to control blood glucose to the levels of 4~7 mmol/L and make urine glucose negative.The rats were sacrificed in 16 and 24 weeks respectively.Blood glucose(BG),serum creatinine(Scr)and 24 h urine protein(24 h UP)were measured with biochemical methods.The pathological changes of renal tissue were observed.Immunohistochemistry and western blot were employed to assay the expression of PTEN,CollagenⅣ,FN,E-cadherin,and α-SMA protein in rat renal tissue.In addition,the expression of PTEN mRNA was examined with RT-PCR.Results: BG,Scr,and 24 h UP of group DM were significantly higher than those of group N(P<0.05),and renal tissue presented fibrosis changes in group DM at different time points.BG,Scr,and 24 h UP of group DMA were significantly lower than those of group DM(P<0.05),and renal fibrosis lesions obviously alleviated.The PTEN protein and mRNA levels in group DM were significantly lower than those in group N at different time points,and the expression of E-cadherin was lower and α-SMA,Collagen Ⅳand FN protein were higher than those in group N.The expression of PTEN protein,mRNA and E-cadherin in group DMA were significantly higher than those of group DM(P<0.05),while the expression of α-SMA,Collagen Ⅳ and FN protein were lower than those of group DM.Conclusions: Blood glucose control can up-regulate the expression of PTEN in renal tubular epithelial cells and delay the process of tubular epithelial-mesenchymal transition(EMT) and alleviate renal fibrosis.