表没食子儿茶素没食子酸酯抑制肾草酸钙结晶形成的研究

Experimental study on the inhibitory effect of epigallocatechin gallate on renal calcium oxalate crystal formation

目的比较不同剂量的表没食子儿茶素没食子酸酯（EGCG）干扰的草酸钙结石模型大鼠肾组织中的丙二醛（MDA）、超氧化物歧化酶（SOD）、谷胱甘肽过氧化酶（GSH-Px）、过氧化氢酶（CAT）含量及草酸钙结晶沉积量的差异。 方法50只SD大鼠随机平均分为5组，分别为空白对照组，肾草酸钙结石模型组和不同剂量EGCG干预组。其中对照组自由饮用纯净水；肾草酸钙结石模型组进行采用1%乙二醇及2%氯化铵进行配制成的造石液每天给予2 ml灌胃；EGCG干预组在模型组处理基础上，每天给予不同剂量[10、30、50 mg/kg]的0.1%EGCG溶液灌胃。28 d后处死大鼠，右肾制备成匀浆，应用硫代巴比妥酸（TBA）法测定MDA含量；用黄嘌呤氧化酶法检测SOD活性，紫外分光光度法测定CAT活性；5，-二硫代双（2-硝基苯甲酸）[DTNB]比色法测定GSH-Px活性；左肾进行常规病理制片苏木素-伊红（HE）染色，偏光显微镜观察结晶沉积。结果空白对照组的MDA浓度（2.74±0.47） μmol/L，SOD浓度（541.71±10.61） Nu/g，CAT浓度（44.49±3.45） U/g及GSH-Px浓度（41.61±2.50）×103 U/g蛋白。与空白对照组比较，肾草酸钙结石模型组中的MDA浓度（5.36±0.54） μmol/L显著升高，而SOD浓度（332.44±12.01） Nu/g、CAT浓度（32.15±1.99） U/g及GSH-Px浓度（21.36±1.58）×103 U/g蛋白显著降低（P＝0.009）；低剂量EGCG干预组，SOD、CAT及GSH-Px水平，分别为（517.41±28.37） Nu/g、（34.42±2.55） U/g及（23.94±2.95）×103 U/g蛋白；中剂量EGCG干预组，SOD、CAT及GSH-Px水平，分别为（545.04±23.84） Nu/g、（35.42±2.61） U/g及（25.10±2.64）×103 U/g蛋白；高剂量EGCG干预组，SOD、CAT及GSH-Px水平，分别为（550.58±16.55） Nu/g、（35.40±2.39） U/g及（26.67±1.93）×103 U/g蛋白；与肾草酸钙结石模型组比较，不同剂量EGCG干扰后的SOD、GSH-Px及CAT水平增加（P＝0.005）；肾组织结晶与EGCG干扰剂量之间呈负相关（r＝－0.483，P＝0.008）。结论不同剂量干扰的EGCG中的肾草酸钙结石模型大鼠中的MDA、SOD及SH-Px含量之间有差异，EGCG可通过降低过氧化损伤抑制草酸钙肾结晶的形成。

ObjectiveTo compare the effects of different dosages of epigallocatechin gallate （EGCG） in calcium oxalate stone rate, to expolre content differences in malondialdehyde （MDA）, superoxide dismutase （SOD）, glutathione peroxidase （GSH-Px）, catalase （CAT） and calcium oxalate crystal deposition. MethodsFifty rats were randomly divided into 5 groups： normal control group, calcium oxalate kidney stone model group and different doses of EGCG intervention group. The control group was permitted to drink purified water freely; model group was given 2 ml stone liquid that was prepared with 1% ethylene glycol and 2% ammonium chloride by the lavage. In the EGCG intervention groups, daily doses of 0.1% EGCG （10, 30, and 50 mg/kg） were given introgastrically on the basis treatment in the model group. Twenty-eight days later, the rats were sacrificed and the right kidney was prepared into homogenate. The thiobarbituric acid （TBA） method was used for the determination of MDA. The xanthine oxidase method was applied to detect SOD activity. CAT activity was tested by ultraviolet spectrophotometry. The DTNB method was used to determine GSH-Px activity. The left kidney tissue was stained by HE method, and crystal deposition was observed by polarizing microscopy. ResultsIn the blank control group, MDA concentration was （2.74±0.47） μmol/L, SOD activity （541.71±10.61） Nu/g, CAT activity （44.49±3.45） U/g and GSH-Px activity （41.61±2.50）×103 U/g·protein. As compared with the blank control group, MDA concentration of calcium oxalate kidney stones in the model group was increased significantly, while the activity of SOD （332.44±12.01） Nu/g, CAT （32.15±1.99） U/g and GSH-Px （21.36±1.58）×103 U/g·protein was significantly decreased （P=0.009）. In the low-dose EGCG group, the activity of SOD, CAT and GSH-Px was （517.41±28.37） Nu/g, （34.42±2.55） U/g and （23.94±2.95）×103 U/g·protein respectively, that in the middle-dose EGCG group （545.04±23.84）, （35.42±2.61） and （25.10±2.64） respectively, and that in the high-dose EGCG group （550.58±16.55） Nu/g, （35.40±2.39） U/g and （26.67±1.93）×103 U/g·protein respectively. As compared with the model group, SOD, GSH-Px and CAT actively was increased in the EGCG groups （P=0.005）. The calcium oxalate crystal deposition in the renal tissue was negatively correlated with the dose of EGCG interference （r=-0.483, P= 0.008）. ConclusionThere were significant differences in MDA, SOD and GSH-Px contents in calcium oxalate stone rats treated with different doses of EGCG, which indicated that EGCG could reduce the formation of calcium oxalate kidney stones by reducing the oxidative damage.