芝麻素对代谢综合征大鼠主动脉内皮功能损伤的保护作用及机制

目的:观察芝麻素对代谢综合征大鼠主动脉内皮功能损伤的保护作用,探讨其可能机制。方法:高脂高糖诱导大鼠代谢综合征24周,于第9周开始连续口服芝麻素(120,60,30mg.kg^-1·d^-1)16周。测血压、血脂、血糖、血清过氧化氢和硝酸盐/亚硝酸盐含量;采用离体灌流系统,观察大鼠主动脉环对累积浓度去氧肾上腺素的收缩反应和对乙酰胆碱及硝普钠诱发的舒张反应;免疫组织化学法观察主动脉内皮型一氧化氮合酶(eNOS)表达和硝基酪氨酸(NT)含量。结果:芝麻素明显降低代谢综合征大鼠血压、血脂、血糖;提高主动脉环对乙酰胆碱诱导的舒张反应;上调主动脉eNOS表达,降低NT含量;升高血清硝酸盐/亚硝酸盐和减少过氧化氢含量。结论:芝麻素具有改善代谢综合征大鼠的内皮功能障碍,其机制可能与其降低氧自由基生成,上调主动脉eNOS表达,增加和(或)恢复NO的生物活性有关。

Effects of Sesamin on Aortic Function in Metabolic Syndrome Rats

Objective:To study the effect of sesamin on aortic function in metabolic syndrome rats,and to explore its possible mechanism.Methods:A high-fat and refined-carbohydrate diet induced metabolic syndrome.Sesamin(120,60,30 mg·kg^-1·d^-1) was given by intragastric administration to metabolic syndrome rats at the 9th week,then lasted for 16 weeks.After 24 weeks,blood pressure,blood fat,blood glucose,hydrogen peroxide and nitrate/ nitrite in serum were determined.In addition,the vascular function test was performed.The thoracic aortic ring of rats was mounted on a bath system.The effect of sesamin on the contraction elicited by phenylephrine and the relaxation induced by acetylcholine and sodium nitroprusside were measured.To explore the mechamism,expression of endothelium nitric oxide synthase(eNOS) and nitrotyrosine in aorta were observed by immunohistochemical method.Results: Sesamin obviously decreased the level of blood pressure,blood fat,blood glucose,serum hydrogen peroxide and increased concentration of nitrate/nitrite in rats;it also enhance the relaxation induced by acetylcholine and raised expression of eNOS and depressed expression of nitrotyrosine in aorta.Conclusion: Sesamin may improve the endothelium-dependent relaxation dysfunction,possibly though decreasing the level of oxyradicals,increasing expression of eNOS in aorta,and raising concentration of NO or recovering its bioactivity.