表没食子儿茶素没食子酸酯对低密度脂蛋白诱导的血管内皮损伤的保护作用

Epigallocatechin Gallate Preventing Low Density Lipoprotein-Induced Endothelial Dysfunction

目的探讨茶多酚主要活性成分表没食子儿茶素没食子酸酯对低密度脂蛋白诱导的大鼠血管内皮功能不全的保护作用及其机制。方法雄性SD大鼠随机分为5组:对照组、低密度脂蛋白组、低密度脂蛋白+表没食子儿茶素没食子酸酯(10 mg/kg)组、低密度脂蛋白+表没食子儿茶素没食子酸酯(50 mg/kg)组和低密度脂蛋白+维生素E(50 mg/kg)组。舌下静脉注射低密度脂蛋白诱发血管内皮功能不全,检测血浆中非对称性二甲基精氨酸、一氧化氮、丙二醛和肿瘤坏死因子含量,并观察离体胸主动脉环的内皮依赖性舒张反应。结果单次静脉注射低密度脂蛋白能明显降低大鼠胸主动脉的内皮依赖性舒张效应,升高血浆中非对称性二甲基精氨酸、丙二醛和肿瘤坏死因子水平,减少一氧化氮的生成(P<0.01)。表没食子儿茶素没食子酸酯(10 mg/kg和50 mg/kg)可显著改善低密度脂蛋白所致的血管内皮舒张功能障碍,降低非对称性二甲基精氨酸、肿瘤坏死因子和丙二醛水平,增加一氧化氮的合成。结论表没食子儿茶素没食子酸酯能显著改善低密度脂蛋白对血管内皮舒张功能的抑制作用,其保护作用可能与降低内源性非对称性二甲基精氨酸水平有关。

Aim To examine whether the protective effect of epigallocatechin gallate （EGCG） on endothehal cells is associated with reduction of asymmetric dimethylarginine （ADMA） concentration in rats treated with low density hpoprotein （EDL）. Methods 40 rats were randomly divided into five groups： control group, EDL group, 10 mg/kg EGCG group, 50 mg/kg EGCG group and Vitamin E group. Vascular endothelial injury was induced by a single injection of native EDL （4 mg/kg） in rats. Vascular endothelium-dependent relaxation to acetylchohne of isolated thoracic aorta and plasma concentrations of ADMA, nitric oxide （NO）, malondialdehyde （MDA） and tumor necrosis factor-α （TNF-α） were analyzed. Results A single injection of LDL markedly inhibited endothelium-dependent relaxation to acetylcholine, increased plasma level of ADMA, MDA and TNF-α, and decreased plasma concentrations of NO. Treatment with EGCG significantly improved the endothehum-dependent vasedilation, decreased tile elevated level of ADMA, MDA, TNF-α, and enhanced the decreased level of NO in the rats treatd with LDL. Conclusions The present results suggest that the beneficial effect of EGCG on endothehal cells may be related to reduction of endogenous ADMA concentration.