肾结石大鼠钠/二羧基转运蛋白1的表达及枸橼酸钾防治机制的研究

Change of Na^+/dicarboxylate cotransporter-1 expression in rats with nephrolithiasis induced by ethylene glycoi and mechanism of potassium citrate prevention

目的 研究肾组织钠/二羧基转运蛋白1(SDCT1)与低枸橼酸尿的关系以及枸橼酸钾的干预作用,探讨肾结石发病的分子机制和防治措施。方法 雄性Wistar大鼠分为对照组、肾结石组及枸橼酸钾干预组。血、尿枸橼酸和草酸采用酶法测定,Northern blot检测大鼠肾组织SDCT1mRNA水平的改变,免疫组织化学观察SDCT1在肾组织的分布及表达变化。结果 与对照组比较,肾结石组第3天尿草酸水平显著升高,枸橼酸水平显著降低,同时肾组织SDCT1mRNA及其蛋白水平上调。第7天SDCT1mRNA及其表达产物增加更为显著,同时尿枸橼酸水平进一步降低,尿钙排泄显著增加,87.5％大鼠有中-大量的草酸钙结石形成。第14天上述改变更为明显,结石形成率达100％。枸橼酸钾干预组各时间点尿草酸水平与肾结石组差异无显著性意义,但尿枸橼酸水平显著高于肾结石组及对照组,肾组织SDCT1mRNA及蛋白表达显著低于肾结石组,与对照组差异无显著性意义;结石形成率显著低于肾结石组;肾小管扩张、炎细胞浸润等病变也明显减轻。结论 肾组织SDCT1表达上调可能是低枸橼酸尿的重要原因,与肾结石的形成有密切关系。枸橼酸钾可下调肾结石大鼠肾组织SDCT1的表达,对肾结石的形成具有明显的干预作用。

Objective To investigate the change of Na+ /dicarboxylate cotransporter (SDCT) 1 expression in renal tissues of rats with nephrolithiasis induced by ethylene glycol (EG) and the mechanism of potassium citrate prevention. Methods Male Wistar rats were divided into control, nephrolithiasis and potassium citrate treated groups. Calcium oxalate crystal deposition and histological changes in kidney were examined by anatomical and light microscope. The plasma and urinary biochemical parameters, such as citrate, oxalate etc., were analyzed by routine biochemical method. The expression of SDCT1 mRNA in kidneys was determined by Northern blot, and the change of SDCT1 protein abundance was detected by immunohistochemistry. Results On day 3, the animals in the nephrolithiasis group had a higher level of SDCT1 mRNA and protein abundance in kidneys, as well as a lower level of citrate in the urine when compared with the control group. However none of the rats in this group had obviously calcium oxalate crystal deposition in kidneys. On day 7 and 14, the expression of SDCT1 mRNA and protein abundance were shown further increase, when the urinary citrate concentration was decreased progressively, and 87. 5% to 100% of the rats in this group displayed a large quantity of calcium crystal deposition in the kidney. In the potassium citrate treated group, both the expression of SDCT1 mRNA and protein abundance were shown almost complete inhibited during the whole experiment time, meanwhile the urinary citrate level was significantly elevated with time; furthermore, the occurrence of the renal crystal deposition decreased to 37. 5% on day 14, and the pathologic changes such as tubular dilation and inflammatory cells infiltration were shown to be alleviated. Conclusions The upregulation of SDCT1 mRNA and protein abundance in kidney has a close relationship with hypocitraturia, which may play an important role in the development of nephroliathisis. The treatment with potassium citrate has a beneficial effect on the experimental nephrolithiasis rats through inhibiting the expression of SDCT1 in the renal tissue.