摘要
目的观察高糖与切应力对肾小管上皮细胞白蛋白受体megalin、cubilin表达的影响并探讨其意义。方法链尿菌素（STZ）腹腔注射SD雄性大鼠制作糖尿病肾病（DN）模型，以健康SD雄性大鼠为对照。于第2、4、6周分别检测尿白蛋白量（24h）；免疫组化法检测各组肾脏megalin、cubilin蛋白的表达。将体外培养的肾近端小管上皮细胞（NRK-52E）分为空白对照组、甘露醇组、高糖组，并以平行板流室系统提供0．5、1．0Pa的切应力处理各组NRK-52E细胞，分别作用1、3、6h。以RT—PCR法检测各组细胞megalin、cubilinmRNA表达。结果对照组肾脏megalin、cubilin蛋白表达水平高于相应时间点DN组（P〈0．05）。肾脏megalin、cubilin表达水平与尿白蛋白量（24h）呈负相关（r=-0．832及-0．815，均P〈0．05）。高糖抑制NRK-52E细胞megalin、cubilinmRNA的表达（P〈0．05）。切应力加载抑制细胞megalin、cubilinmRNA的表达，其抑制作用比单纯高糖更明显，且与切应力大小及作用时间有关（P〈0．05）。结论DN早期高滤过导致滤出液对肾近端小管上皮细胞的切应力增加，其与高糖协同作用可下调细胞megalin、cubilinmRNA的表达，减少肾小管对白蛋白的重吸收，是DN早期微量白蛋白尿发生的机制之一。
Objective To investigate the influence of high glucose and shear strees on the expression of albumin receptor megalin and cubilin in renal proximal tubules of streptozotocin （STZ）-induced diabetic rats and its significance. Methods Diabetic rats were induced by STZ. Proteinuria was measured and the expression of megalin and cubilin was detected by immunohistochemistry at week 2, 4, 6 respectively. Cultured NRK-52E cells were divided into high glucose group, mannitol group and control group. These groups were exposed to shear stress of 0.5 Pa and 1.0 Pa for 1, 3 and 6 h respectively. Megalin and cubilin mRNA expressions were examined by RT-PCR. Results Compared with control group, the expression of megalin and cubilin was significantly decreased in STZ-induced diabetic rats （P〈0.05）. Levels of megalin and cubilin in diabetic rat kidney were negatively correlated with urine albumin excretion respectively （P〈0.05）. Compared to the control group, the mRNA expression of megalin and cubilin was significantly decreased in high glucose group （P〈0.05）. Shear stress significantly down-regulated the mRNA expression of megalin and cubilin in a magnitude- and time-dependent manner （P〈0.05）. Conclusion Increased tubular flow shear stress and high glucose down-regulate the expression of megalin and cubilin, and decrease albumin absorption in renal proximal tubular cells, which may play a role in trigering microalbuminuria in the early-stage of DN.
出处
《中华肾脏病杂志》
CAS
CSCD
北大核心
2008年第2期125-129,共5页
Chinese Journal of Nephrology
