肾脏雌激素受体亚型表达分布及补肾中药防治肾损害的受体机制

Expression and distribution of estrogen receptors in kidney and the underlying mechanism of replenishing kidney recipe for preventing kidney damage

目的:观察雌激素受体α和β在大鼠肾脏中的表达、分布情况,分析补肾中药防治肾损害的受体机制。方法:实验于2000-09/2002-07在河北医科大学生化实验室完成。选用健康雌性SD大鼠45只,按随机数字法分为3组,即正常对照组、肾脏损伤模型组及中药防治组,每组15只。肾脏损伤模型组和中药防治组大鼠每天腹腔注射1mL9g/L的灭菌AlCl3溶液复制肾脏损伤模型,正常对照组注射1mL灭菌生理盐水,每连续注射3d,间隔1d,共计72d。中药防治组大鼠每天灌胃1mL生药含量为2.6g/mL的补肾中药复方煎剂(由淫羊藿、熟地、制首乌、黄芪、当归、郁金、石菖蒲、茯苓和川芎9味中药组成,由石家庄乐仁堂药业有限公司提供,每付生药含量为125g),正常对照组和肾脏损伤模型组灌胃等量自来水。每连续灌胃7d,间隔1d,共计72d。应用免疫组织化学方法检测雌激素受体α和β在各组大鼠肾组织中的表达水平和分布区域,应用放射免疫分析法测定各组大鼠血清雌二醇水平。结果:45只大鼠全部进入结果分析,无脱失。①雌激素受体亚型在各组大鼠肾组织中的表达和分布情况比较:正常对照组大鼠肾脏皮质和髓质的远曲小管和近曲小管上皮细胞胞浆中都有雌激素受体α和β阳性颗粒,两种受体亚型的髓质反应信号均比皮质强。肾脏损伤模型组大鼠肾脏皮质雌激素受体β反应信号减弱;髓质雌激素受体α反应信号增强。中药防治组大鼠肾水肿基本消失,皮质雌激素受体β反应信号增强至近正常水平,髓质雌激素受体α反应信号降低至近正常水平。②各组大鼠的血清雌二醇水平比较:肾脏损伤模型组大鼠血清雌二醇水平显著低于正常对照组[(19.0±0.6,40.0±0.1)pmol/L,P<0.01],中药防治组大鼠血清雌二醇水平与肾脏损伤模型组相近[(18.0±0.6)pmol/L,P>0.05]。结论:AlCl3导致肾水肿时,肾脏皮质雌激素受体β表达减弱,髓质雌激素受体α表达增强,血清雌二醇水平降低。补肾中药具有雌二醇样作用,通过拮抗皮质雌激素受体β表达减弱和髓质雌激素受体α表达增强而发挥其肾脏保护作用。

AIM： To determine the expression and immunoloealization of estrogen receptor （ER） α and ERβ in the rat＇s kidney, and explore the underlying mechanism of the replenishing kidney herbs on preventing kidney damage. METHODS： The experiment was conducted in the Biochemistry Laboratory of Xinxiang Medical College from September 2000 to July 2002. Fortyfive healthy female SD rats were randomized into 3 groups, namely control group, model group and herb group, each containing 15 rats. Kidney damage was induced by intraperitoneal injection of 9 g/L AlCl3 solution （1 mL） in the rats of model group and herb group. While the normal control rats were injected with 1 mL saline for successive 3 days in the interval of 1 day, totally for 72 days. The rats of herb group were injected intragastrically of replenishing kidney herbs decoction including 2.6 g/mL crude drug in 1 mL （consisting of Korean epimedium herb, Radix Rehmanniae Paparata, fleeceflower root, membranous milkvetch root, Chinese angelica, zedoary turmeric root-tuber, tatarinowii sweetflag rhizome, tuckahoe and szechwan lovge rhizome, provided by Shijiazhuang Lerentang Pharmaceutical Company, and 125 g crude drug in per decoction）, and the rats of control group and model group were given intragastric infusion of equal tap-water for continuous 7 days with the interval of 1 day, totally 72 days. Serum estradiol （E2） level was measured by radioimmunoassay, whereas both expression and localization of ERα and ERβ were determined by immunohistochemistry. RESULTS： Totally 45 rats entered the result analysis without loss.①The expression and localization of ER isoforms in the kidney tissues： Both ERα and ERβ were dominantly expressed in the epithelium cells of proximal and distal convoluted tubules in both cortex and medulla of kidney. And the expressions of both ERs were higher in medulla than in cortex. In the model group, cortical ERα was hypoexpressed, while medullary ERβ was hyperexpressed. In the herb group, the kidney edema ahnost disappeared in the rats, and both cortical ERβ and medullary ERα recovered to the normal levels in edematous kidney.②Serum E2 level of the rats was decreased significantly in model group than in control group [（19.0±0.6,40.0 ±0.1） pmol/L, P 〈 0.01]. And there was similar serum E2 level between herb group and model group [（18.0±0.6） pmol/L, P 〉 0.05]. CONCLUSION： Cortical ERα hypoexpress, while medullary ERβ hyperexpress, and serum E2 level decreases in the edematous kidney induced by AlCl3. The replenishing kidney recipe may possess E2-like action on preventing AlCl3-induced edema of kidney by depressing the expression of ERβ and increasing the expression of ERα.