甘氨酸对高果糖饮食诱发高血压大鼠血管内皮功能的影响

目的 探讨甘氨酸对高果糖饮食诱导高血压大鼠内皮功能的影响及降压机制.方法 模型组大鼠以8％果糖水喂养,甘氨酸+果糖组给予8％果糖+1％甘氨酸水喂养.每月测量大鼠体重和收缩压,分别于4月、8月处死动物,检测血糖、血浆胰岛素、内毒素、肿瘤坏死因子α(TNF-α)、白细胞介素6(IL-6)、一氧化氮(NO)及内皮素1(ET-1)变化,计算胰岛素抵抗指数(HOMA-IR).免疫组织化学检测血管内皮型一氧化氮合酶(eNOS)表达,实时荧光定量PCR分析内皮素A受体(ETA-R) mRNA表达.结果 模型组大鼠3月～6月体重明显增加,3月后收缩压升高,4月和8月血糖、血浆胰岛素、HOMA-IR、内毒素、TNF-α、IL-6、ET-1水平及ETA-R mRNA表达均升高,血浆NO水平及eNOS表达下降,但各阶段之间上述指标无明显差异.甘氨酸+果糖组4月和6月体重、收缩压显著降低,4月和8月血浆胰岛素、HOMA-IR、内毒素、TNF-α、IL-6、ET-1水平及ETA-RmRNA表达明显降低,4月血浆NO水平及eNOS表达显著提高.结论 甘氨酸对高果糖饮食诱导的早期高血压具有明显降低作用,其机制与甘氨酸减轻内毒素血症改善胰岛素抵抗及内皮功能紊乱有关.

Effects of Glycine on Vascular Endothelial Function in Rats with A High-fructose Diet Induced Hypertension

Aim To investigate the effects of glycine on endothelial function in rats with a high-fructose diet induced hypertension and the mechanisms of glycine on lowering hypertension.Methods Model group rats were fed with 8% fructose water,and glycine intervention group rats were fed with water containing 8% fructose and 1% glycine.The body weight and systolic blood pressure were measured monthly,and the animals were killed in 4 th month and 8 th month respectively.The levels of plasma glucose,insulin,endotoxin,TNF-α,IL-6,NO and endothelin-1(ET-1) were detected,and HOMA-IR was calculated.The expression of endothelial nitric oxide synthase(eNOS) was determined by immunohistochemistry,and the expression of endothelin A receptor(ETA-R) mRNA was analyzed by RT-PCR.Results The body weight and systolic blood pressure were increased in model group after 3 months.The levels of plasma glucose,insulin,HOMA-IR,endotoxin,pro-inflammatory cytokines,ET-1 and the expression of ETA-R mRNA were increased in model group,but the levels of plasma NO and the expression of eNOS were decreased in 4 th and 8 th month.However,there was no significance of the parameters at different stages.Glycine significantly reduced the weight gain at 4 th month and 6 th month,and reduced the elevated systolic blood pressure in 4 th month to 6 th month,and significantly decreased the levels of plasma insulin,HOMA-IR,endotoxin,pro-inflammatory cytokine,ET-1 and the expression of ETA-R mRNA in 4 th and 8 th month,and significantly increased the levels of plasma NO and the expression of eNOS in 4 th month.Conclusions Glycine can ameliorate early hypertension induced by a high-fructose diet,which may be related to glycine lowering endotoxemia,insulin resistance and ameliorating the endothelial dysfunction.