用高胰岛素-正葡萄糖钳夹实验探讨增龄对Wistar大鼠胰岛素敏感性的影响

目的探讨增龄对Wistar大鼠体重、空腹血糖、空腹胰岛素、空腹游离脂肪酸(FFA)水平及胰岛素敏感性的影响。方法将雄性Wistar大鼠45只分为4月龄组、14月龄组和24月龄组,每组15只,行高胰岛素-正葡萄糖钳夹实验,观察空腹血糖、空腹胰岛素、血清FFA和胰岛素敏感性的变化。结果 3组大鼠的体重差异有统计学意义(P<0.05,P<0.01)。与4月龄组比较,14月龄组和24月龄组大鼠空腹胰岛素、胰岛素抵抗指数明显升高(P<0.01),24月龄组大鼠血清FFA明显高于4月龄组(P<0.01);与4月龄组比较,14月龄组和24月龄组大鼠稳态葡萄糖输注速率明显降低,差异有统计学意义(P<0.01)。多元线性回归分析显示,增龄与胰岛素敏感性呈负相关。结论随着年龄的增加,大鼠空腹血糖无明显差异,空腹胰岛素和FFA均明显增加,胰岛素的敏感性降低,胰岛素抵抗加重。脂肪、肌肉和肝脏可能参与了增龄介导的胰岛素抵抗。

Exploration of effect of aging on insulin sensitivity of Wistar rats by using the euglycaemic-hyperinsulinaemic clamp

Objective To elucidate the effect of aging on insulin sensitivity of Wistar rats. Methods Forty-five male Wistar rats were divided into 3 groups of 15 rats each: 4 month old group, 14-month-old group and 24-month-old group. Euglycaemic-hyperinsulinaemic clamp technique was used to observe the fasting blood glucose, blood insulin and free fatty acid. Results The body weight of 4-month-old group,14-month-old group and 24-month-old group had statistical difference (P<0.01). There was no significant difference in fasting blood glucose among the three groups. Compared with 4-month-old group, the fasting blood insulin,serum FFA and insulin resistance index significantly increased in 14-month-old group and 24-month-old group,with statistically significant difference (P<0.01). The result of euglycaemic-hyperinsulinaemic clamp test displayed that compared with 4-month-old group, the glucose infusion rate of 14-month-old group, and 24-month-old group was significantly decreased, with statistically significant difference (19<0.01). Multivariate regression analysis showed that aging was negatively correlated with insulin sensitivity. Conclusions The data support that with growing of age, the blood fasting insulin and free fatty acid are increased , but the insulin sensitivity is decreased, and the body is becoming more insulin resistant. It provides a possible explanation for the increased incidence of type 2 diabetes in the elderly.