不同方式运动对胰岛素抵抗大鼠骨骼肌脂肪转运、合成和分解的影响及机制

Effects of different types of exercise on lipid uptake,synthesis and oxidation in skeletal muscles of insulin-resistant rats

为了考察有氧运动和抗阻运动对高脂膳食诱导的胰岛素抵抗(insulin resistance,IR)大鼠骨骼肌脂代谢的影响及机制,本研究采用高脂膳食喂养10周龄雄性Sprague-Dawley(SD)大鼠进行IR造模,将造模成功的大鼠分为IR对照组(IR)、有氧运动组(AE)和抗阻运动组(RE),另外增加普通膳食安静对照组(CON)。8周运动干预后取血清测空腹血糖(fasting blood glucose,FBG)、血清胰岛素(fasting insulin,FIN)、胰高血糖素(glucagon,Glu)、血脂四项和游离脂肪酸(free fatty acid,FFA)含量,取骨骼肌测甘油三酯(triglyceride,TG)和FFA含量。Westernblot检测股四头肌FAT/CD36、CPT-1、SCD-1和PPARγ蛋白表达。结果显示:(1)IR导致大鼠FBG、FIN及低密度脂蛋白胆固醇(low density lipoprotein cholesterol,LDL-C)含量显著升高,有氧运动和抗阻运动显著降低了IR大鼠上述指标,有氧运动还增加了高密度脂蛋白胆固醇(high density lipoprotein cholesterol,HDL-C)含量;(2)IR对骨骼肌TG含量影响不显著,但增加了FFA含量;两种运动均减少了IR大鼠骨骼肌TG含量,但有氧运动显著增加了大鼠骨骼肌FFA含量,抗阻运动则显著降低了FFA含量;(3)IR增加了大鼠骨骼肌FAT/CD36、SCD-1和PPARγ蛋白表达,降低了CPT-1蛋白表达;两种方式的运动均可降低IR大鼠FAT/CD36、SCD-1和PPARγ蛋白表达,增加CPT-1蛋白表达。综上所述,有氧运动和抗阻运动均可降低IR导致的骨骼肌细胞脂肪酸摄入和脂质积累,增加脂肪酸氧化分解,进而改善高脂膳食诱发的IR;其中抗阻运动效果更显著。

The present study aims to investigate the effects of aerobic exercise and resistance exercise on lipid metabolism of skeletal muscle in high-fat diet(HFD)-induced insulin-resistant(IR)rats and the underlying mechanisms.Male Sprague-Dawley(SD)rats at age of 10 weeks were fed with HFD for 10 weeks to establish IR model.The IR rats were then randomly assigned into 3 groups,including IR control(IR)group,aerobic exercise(AE)group and resistance exercise(RE)group.An additional chow diet sedentary control(CON)group was used as well.Fasting blood glucose(FBG),insulin(FIN),glucagon and lipids,as well as triacylglycerol(TG),free fatty acids(FFA),and the protein expression of fatty acid translocase/cluster of differentiation 36(FAT/CD36),carnitine palmitoyltransferase-1(CPT-1),stearoyl-CoA desaturase-1(SCD-1)and peroxisome proliferators-activated receptorsγ(PPARγ)in skeletal muscles were measured after 8-week exercise interventions.The results showed that the contents of FBG,FIN,and LDL-C were increased by IR compared with CON group,and significantly decreased by aerobic exercise and resistance exercise;while aerobic exercise induced an increase in HDL-C as well.Furthermore,IR exhibited no significant effects on TG content of skeletal muscles,but significantly increased FFA level.Both aerobic and resistance exercise led to a decrease in TG content,and FFA level was increased by aerobic exercise but deceased by resistance exercise.In addition,the protein expression of FAT/CD36,SCD-1 and PPARγwas increased and that of CPT-1 was decreased by IR,while both types of exercise resulted in a decrease in the protein expression of FAT/CD36,SCD-1 and PPARγ,and an increase in CPT-1.In conclusion,aerobic and resistance exercise may attenuate IR through decreasing HFD-induced ectopic fat deposition and increasingβ-oxidation of fatty acids in skeletal muscle cells,and resistance exercise shows a greater improvement in lipid metabolism of skeletal muscles than aerobic exercise.