饱和脂肪酸对AMPKa表达和活性的影响

Effects of high saturated fatty acid diet on the expression and activity of AMPKa

目的探讨饱和脂肪酸对大鼠骨骼肌蛋白激酶(AMPKa)亚基表达及活性的影响,确定其在脂毒性发生中的地位和作用,为有效预防和控制脂毒性提供科学依据。方法雄性Wistar大鼠随机分为3组,每组10只,即对照组、高脂组和高脂加AMPKa激活剂组[二甲双胍50 mg/(kg.d),n=10]。喂养20周后,测定大鼠空腹和服糖后2 h血糖;用体外骨骼肌糖摄取试验评价大鼠骨骼肌胰岛素敏感性,Western blot法测定大鼠骨骼肌中AMPKa亚基和磷酸化AMPKa亚基蛋白水平。结果(1)与对照组比较,高脂组大鼠空腹血糖增加21.5%(P<0.05),服糖后2 h血糖增加28.3%(P<0.05),骨骼肌基础和胰岛素刺激后的糖摄取分别下降37.2%(P<0.05)和57.89%(P<0.01);(2)高脂组大鼠骨骼肌P-AMPKa和总AMPKa亚基蛋白水平分别下降46.1%(P<0.05)和79.4%(P<0.05);(3)与高脂组比较:二甲双胍显著上调AMPKa亚基的表达(P<0.05)和活性增加(P<0.05)。结论饱和脂肪酸通过降调AMPKa亚基表达和活性诱导大鼠胰岛素抵抗。

Objective To study the role of AMPKa in high saturated fatty acid diet-induced insulin resistance. Methods Male Wistar rats were randomly divided into three groups. They were control group（ NC, n = 10）, high-fat diet group （HF, n = 10）and mefformin-treated group. （HF ＋ Met, n = 10）. Mefformin was administrated orally with the dose of 50 mg/（ kg. d）. After feeding for 20 weeks,fasting and glucose-loaded 2 h blood glucose levels were measured. The ability of glucose uptake of rat skeletal muscle was detected. Protein levels of total AMPKa subunit or P-AMPKa subunit of rats＇ skeletal muscle were measured using Western blot. Results （1） Compared with control group, high-fat diet elevated both fasting and glucose-loaded 2 h blood glucose levels （P 〈 0.05）, accompanied with decreased basal （ P 〈 0.05） and insulin-stimulated （ P 〈 0.01 ） glucose uptake in isolated skeletal muscle. （2） Highfat diet impaired both the protein expression（ P 〈 0.05 ） and activity （ P 〈 0.05 ） of AMPKa subunit. （ 3 ） Compared with HF group, administration of mefformin could increase both the expression and activity of AMPKa, accompanied with amelioration of insulin sensitivity. Conclusion High saturated fatty acid diet impairs both the expression and activity of AMPKa. The alternations of AMPKa expression and activity might contribute to, at least partly, the pathophysiology of insulin resistance.