不同膳食脂肪对糖耐量及胰岛素敏感性的影响

EFFECT OF DIFFERENT DIETARY FAT ON GLUCOSE TOLERANCE AND INSULIN SENSITIVITY

目的:比较4种膳食脂肪对大鼠糖耐量及胰岛素敏感性的影响。方法:将50只SD大鼠随机分为5组,分别为紫苏油组、葵花籽油组、橄榄油组、猪油组和基础饲料组。各膳食脂肪组大鼠的脂肪摄入量占总能量的30.4%。喂养6 w后,进行口服葡萄糖耐量试验(OGTT),测定血清胰岛素、甘油三酯、总胆固醇等指标,并计算胰岛素敏感指数(ISI)。同时分离附睾脂肪垫并称重。结果:与基础饲料组相比,猪油组大鼠葡萄糖餐后2 h血糖及胰岛素显著升高,ISI显著降低;葵花籽油组和橄榄油组大鼠的餐后2 h血糖显著低于猪油组,ISI显著高于猪油组;紫苏油组大鼠空腹及餐后2h血糖、胰岛素水平均显著低于猪油组,ISI高于猪油组,其中空腹血糖还低于葵花籽油组、橄榄油组和基础饲料组,ISI高于上述组。紫苏油组血清甘油三酯、总胆固醇水平显著低于猪油组和基础饲料组,大鼠附睾脂肪垫相对重量显著低于猪油组。结论:猪油可促使胰岛素抵抗及高血糖的发生,而紫苏油可提高大鼠胰岛素敏感性、改善糖代谢;葵花籽油和橄榄油对胰岛素敏感性和糖耐量的作用介于紫苏油和猪油之间。紫苏油对糖代谢的有利作用可能与其降低血中甘油三酯水平、减少体内脂肪堆积有关。

Objective: To investigate the effects of different dietary fat on insulin sensitivity and glucose tolerance in rats. Methods: Fifty adult male Sprague-Dawley rats were randomly assigned to five groups and fed on basal diet (low fat diet) and four test diets containing 30.4% fat of total energy as lard, perilla oil, sunflower oil or olive oil respectively for 6 w. An oral glucose tolerance test (OGTT) was performed and blood samples were taken for measurement of serum insulin, triglyceride (TG) and total cholesterol (TC) level. Insulin sensitivity index (ISI) was calculated and epididymal fat pad was weighed. Results: In comparison with rats fed low fat, rats fed lard had a low ISI and a high serum glucose level 120 min after glucose load. The ISI in groups of sunflower oil and olive oil was markedly higher than in lard group, whereas serum glucose at 120 min was significantly lower. Serum glucose and insulin level both at 0 min and 120 min were significantly lower and ISI was higher in perilla oil group than that in lard group. Moreover, rats fed perilla oil had a low fasting glucose and a higher ISI compared with rats fed sunflower oil, olive oil and low fat respectively. Serum TC and TG were significantly lower in rats fed perilla oil than in rats fed low fat and lard respectively. Relative epididymal fat pad weight was lower in rats fed perilla oil than in rats fed lard. Conclusion: Perilla oil is effective in increasing insulin sensitivity and improving glucose metabolism in rats, and the effects of sunflower oil and olive oil are between that of perilla oil and lard. The hypoglycemic effect of perilla oil might be mediated, at least in part by reducing triglyceride level and body fat accumulation.