有氧运动改善高脂膳食诱导的胰岛素抵抗:增强骨骼肌线粒体融合与分裂及功能

Adaptation of Mitochondrial Dynamics Is Probably Involved in Aerobic Exercise Prevention of Insulin Resistance Induced by High-fat-diets in Mice

目的:研究高脂膳食诱导胰岛素抵抗(IR)发生中骨骼肌线粒体融合与分裂的改变和长期耐力训练对其影响,为深入探讨IR发生的分子病理学机制以及运动防治IR的机制提供依据。方法:雄性C57BL/6小鼠通过8周高脂膳食诱导IR,再分别将正常和IR小鼠分为安静组和运动组,即正常膳食对照组(NS)、正常膳食运动组(NE)、高脂膳食对照组(HS)、高脂膳食运动组(HE),各运动组进行8周有氧运动训练。检测空腹血糖、胰岛素。提取骨骼肌线粒体测定呼吸功能和ATP合成酶活力。实时荧光定量PCR和Western blot分别测定骨骼肌Mfn2、Opa1、Drp1、Fis1的mRNA和蛋白表达。结果:(1)HS组小鼠空腹血糖、胰岛素和胰岛素抵抗指数均显著高于NS组(P<0.01);骨骼肌线粒体态3呼吸速率、呼吸控制比和ATP酶合成活力均显著低于NS组(P<0.01);Mfn2蛋白显著低于NS组(P<0.01),Drp1和Fis1显著高于NS组(P<0.01)。(2)HE组小鼠空腹血糖、胰岛素和胰岛素抵抗指数均显著高于HS组(P<0.01);骨骼肌线粒体态3呼吸速率、RCR和ATP酶合成活力均显著高于HS组(P<0.01);Mfn2、Opa1和Drp1蛋白显著高于HS组(P<0.01,P<0.05,P<0.01)。结论:高脂膳食诱导IR的小鼠骨骼肌线粒体趋于分裂,呼吸功能和ATP合成能力下降,可能是高脂膳食诱导IR的机制之一。长期有氧运动训练使正常和IR小鼠骨骼肌线粒体融合和分裂均增强,促进线粒体呼吸功能和ATP合成能力,有利于预防和改善IR。

Objective To investigate the effect of long-term aerobic exercise on skeletal muscle mitochondrial dynamics （fusion and fission） and its function on insulin resistance （IR） induced by high-fat-diet in mice. Methods C57BL/6 mice were fed with high fat diet for 8 weeks to induce IR. Then, normal mice and IR mice divided into 4 groups： normal diet control （NS） , normal diet plus exercise （NE） , high-fat diet control （HS） and high-fat diet plus exercise （HE） . Mice were fed and/or trained for 8 weeks. Fasting blood glucose concentration and fasting serum insulin level weremeasured to evaluate IR. Respiratory control ratio （RCR） and ATP synthesis activity in isolated skeletal muscle mitochondria were detected. Skeletal muscle mRNA and Protein levels of Mfn2, Opal and Drpl, Fisl were measured by Real-time PCR and Western-blot respectively. Results （ 1 ） Compare with NS group, the fast blood glucose, fast serum insulin and HOMA-IR of mice in HS group were significantly higher （P 〈 0.01 ） . The skeletal muscle mitochondrial respiratory rate of states 3, RCR and ATP synthesis activity were significantly lower （P 〈 0.01 ） . The protein level of Mfn2 was significantly lower （P 〈 0.01 ） , Drpl and Fisl were significantly higher （P 〈 0.01 ） . （2） Compare with HS group, the fast blood glucose, fast serum insulin and HOMA-IR of mice in HE group were significantly lower （P 〈 0.01 ） . The skeletal muscle mitochondrial respiratory rate of states 3, RCR and ATP synthesis activity of mice in HE group were significantly higher （P 〈 0.01 ） . The protein levels of Mfn2, Opal and Drplwere significantly higher （P 〈 0.01, P 〈 0.05, P 〈 0.01 ） . Conclusion The mitochondria of the IR mice induced by high fat diet inclined to fission; the decreased of mitochondrial respiratory function and ATP synthesis activity, might be involved in the pathogenesis of high fat diet induced IR. Long-time aerobic training enhanced both fusion and fission of skeletal muscle mitochondria and improved the respiratory function and ATP synthesis activity of mitochondria, might be helpful to prevent and cure IR.