中药黄芪对肥胖大鼠内皮血管舒张功能的影响

Radix Astragali Improves Impaired Endothelial Dependent Vasodilation in Obese Rat

目的研究黄芪对肥胖大鼠内皮依赖性与非内皮依赖性血管舒张功能的影响,为代谢综合征患者早期药物干预治疗提供确切的实验依据。方法15只SD雄性大鼠分为3组。对照组予普通饲料喂养,肥胖组予高脂饲料喂养,黄芪干预组高脂饲料喂养的同时饮用黄芪液。6周后处死动物,处死前空腹12h,处死后采集心脏血液,检测血浆生化指标,观察各组动物体质量变化,计算体脂比,取出主动脉置于器官浴槽中,观察离体主动脉环对乙酰胆碱或硝普钠的舒张反应。结果肥胖组动物脂代谢紊乱,血浆甘油三酯、总胆固醇及游离脂肪酸浓度明显升高,平均体质量较对照组增加23%,腹腔平均脂肪质量较对照组增加1.4倍,体脂比显著高于对照组。黄芪干预组动物平均体质量与肥胖组基本一致,腹腔平均脂肪质量较肥胖组减少32%,体脂比介于对照组与肥胖组之间,血浆甘油三酯水平明显下降,游离脂肪酸水平有所下降,但差异无统计学意义。肥胖大鼠内皮血管舒张功能明显受损,其最大舒张程度仅为对照组的46%。黄芪干预组动物内皮依赖性血管舒张功能较肥胖组改善。结论黄芪对肥胖动物受损的血管内皮细胞功能具有确切的保护作用。

Objective To investigate the effects of Radix Astragali, a traditional Chinese medicine, on endothelium-dependent and non-dependent vasodilation in food-induced obese SD rats. Methods Fifteen male Sprague-Dawley rats were divided into 3 groups： The control group （n-= 5） was fed with normal chow; The obese group （n=5） was fed with high fat chow; The Astragali group （n=5） was fed with high fat chow and Astragali in drinking water. At the end of six weeks, all rats were killed and heart blood samples were taken to assess serum triglyeeride, total cholesterol, and free fat acid. The thoracic aortas rings were harvested and equilibrated in Krebs- Henseleit solution. To measure the endothelium-dependent relaxation, the aortas rings were constricted in response to norepinephrine. After a stable contraction plateau was reached, cumulative dose-response for relaxation to Acetylcholine （10^-8-10^-4 mol/L） were obtained in each rings. Identical experiments were conducted with 10^-8-10^-4 mol/L sodium nitroprusside as the endothelium independent vasorelaxting agent. Responses to vasodlilators were expressed as percentage relaxation in all preconstricted state. Results The ratio of celiac fat and body weight in the obese rats was higher than in the controls. The levels of serum triglyceride, total cholesterol, and free fat acid were elevated in the Obese Group compared with the Control Group. The Astragali Group had lower triglyceride and free fat acid levels than the Obese Group. Compared with the rats with high-fat diet, the rats fed with Astragali lost about 32% of celiac fat. Aeetylcholine （10^-8-10^-4 mol/L） caused a concentration-dependent relaxation in all preconstricted aortic rings. Compared to the control group, maximal endothelium dependent relaxation in the obese group was impaired （P〈0.05）. In the Astragali group, the relaxation to acetylcholine was intermediate between control and obese group （P 〈 0. 05）. Sodium nitroprusside （10^-8-10^-4 mol/L） induced potent relaxation （endothelium independent relaxation） in all rat aortic rings that did not differ statistically between groups. Conelusion Astragalus has salutary effects on impaired endothelial dysfunction in the context of obesity.