六周有氧运动改善动脉粥样硬化小鼠骨骼肌氧化损伤和促进肌肉因子生成

Six-week Aerobic Exercise Improves Oxidative Damage of Skeletal Muscles and Promotes Myokine Production in Atherosclerotic Mice

动脉粥样硬化累及外周动脉能引起骨骼肌病变,其中氧化损伤是骨骼肌病变的重要表现,并且动脉粥样硬化也会减少有益肌肉因子的生成分泌。肌肉因子鸢尾素(irisin)、肌肉素(musclin)和BAIBA被认为参与改善动脉粥样硬化。然而,目前尚不明确动脉粥样硬化诱导骨骼肌病变的分子机制,以及有氧运动训练对其骨骼肌氧化损伤和肌肉因子生成的影响。本研究采用高脂饮食(HFD)喂食载脂蛋白E基因敲除(ApoE-/-)小鼠12周,以建立动脉粥样硬化模型,然后观察动脉粥样硬化小鼠骨骼肌中的氧化损伤、Nrf2抗氧化信号通路以及肌肉因子鸢尾素、musclin和BAIBA生成的变化,并通过6周有氧运动观察对动脉粥样硬化小鼠骨骼肌氧化损伤的改善作用,以及鸢尾素、肌肉素和BAIBA生成的影响。ApoE-/-小鼠在HFD喂养12周时,采用多普勒超声评估动脉粥样硬化病变,与标准饮食喂养的野生型(WT)小鼠相比,ApoE-/-小鼠主动脉内-中膜厚度(P<0.01)、峰值血流速度(P<0.05)和阻力指数(P<0.05)显著增加,血浆甘油三酯(TG)、总胆固醇(TC)和低密度脂蛋白胆固醇(LDL-C)水平明显增加,高密度脂蛋白胆固醇(HDL-C)水平明显降低(P<0.01),小鼠发生动脉粥样硬化和高脂血症。动脉粥样硬化鼠继续HFD喂养6周,与WT小鼠相比,骨骼肌肌纤维MyHC-IIb(P<0.01)、MyHC-IIx(P<0.01)和MyHC-IIa(P<0.05)mRNA表达量均显著降低,骨骼肌4-HNE修饰蛋白质表达、蛋白质羰基含量和ROS水平显著增加(P<0.05),Nrf2(P<0.05)和p-Nrf2(P<0.01)及其下游抗氧化蛋白质CAT(P<0.01)、GPX1(P<0.05)和SOD1(P<0.01)表达显著降低,Gss mRNA表达量(P<0.05)、GSH含量(P<0.01)以及GSH/GSSG(P<0.05)均显著减少,GSSG含量(P<0.05)显著增加,血浆鸢尾素和肌肉素水平明显降低(P<0.05)。经6周有氧运动,动脉粥样硬化鼠血浆TG(P<0.05)、TC(P<0.01)和LDL-C(P<0.05)显著降低,骨骼肌中4-HNE修饰蛋白质表达和蛋白质羰基含量显著减少(P<0.05),p-Nrf2(P<0.01)、CAT(P<0.05)、GPX1(P<0.05)和NQO1(P<0.05)蛋白质表达明显增加,Gss(P<0.05)、Gsr(P<0.05)、Gclc(P<0.05)、Gclm(P<0.01)mRNA表达量以及GSH含量和GSH/GSSG(P<0.05)均明显增加,骨骼肌中鸢尾素前体Fndc5 mRNA表达量(P<0.05)、血浆鸢尾素(P<0.01)和肌肉素(P<0.05)水平、骨骼肌肌肉素含量(P<0.01),以及骨骼肌中BAIBA生成相关基因Acads(P<0.01)、Hadha(P<0.01)和Hadh(P<0.05)mRNA表达均显著增加。上述研究结果表明,动脉粥样硬化降低了小鼠骨骼肌的抗氧化水平,增加了其氧化应激,而经6周有氧运动激活了动脉粥样硬化鼠骨骼肌Nrf2信号通路,明显改善和减缓了骨骼肌的氧化损伤。此外,6周有氧运动也有效促进了动脉粥样硬化鼠骨骼肌中肌肉因子鸢尾素、BAIBA和肌肉素的生成。

Atherosclerosis involving peripheral arteries can cause skeletal muscle lesions,in which oxidative damage is an important manifestation,and atherosclerosis also reduces the production and secretion of beneficial myokines.Irisin,musclin andβ-aminoisobutyric acid(BAIBA)are thought to be involved in improving atherosclerosis.However,the molecular mechanism of atherosclerosis-induced skeletal muscle lesions and the effects of aerobic exercise training on the oxidative damage of skeletal muscle and myokine production remain unclear.In this study,apolipoprotein E knockout(ApoE-/-)mice were fed with high-fat diet(HFD)for 12 weeks to establish an atherosclerosis model.The changes of oxidative damage,the Nrf2 signaling pathway and the production of irisin,musclin and BAIBA in skeletal muscles of atherosclerotic mice were observed.Six weeks of aerobic exercise was used to observe the improvement of oxidative damage and the production of irisin,musclin and BAIBA in skeletal muscle of atherosclerotic mice.ApoE-/-mice were assessed for atherosclerotic lesions by Doppler ultrasound after 12-week HFD feeding.Compared with wild-type(WT)mice fed with a standard diet,aortic intima-media thickness(P<0.01),Vmax(P<0.05)and RI(P<0.05)in ApoE-/-mice were significantly increased,as plasma triglycerides(TG),total cholesterol(TC)and low-density lipoprotein cholesterol(LDL-C)levels were significantly increased,the high-density lipoprotein cholesterol(HDL-C)level was decreased(P<0.01),indicating that ApoE-/-mice developed atherosclerosis and hyperlipidemia.After atherosclerotic mice continued to be fed with HFD for six weeks,compared with WT mice,the mRNA expressing of My-HC-IIb(P<0.01),MyHC-IIx(P<0.01)and MyHC-IIa(P<0.05)in skeletal muscles of atherosclerotic mice were significantly decreased;the expression of 4-HNE-modified proteins,protein carbonyl contents and ROS levels in skeletal muscles were increased(P<0.05);the expressions of Nrf2(P<0.05),p-Nrf2(P<0.01)and their downstream antioxidant proteins CAT(P<0.01),GPX1(P<0.05)and SOD1(P<0.01)were significantly decreased;Gss mRNA expression(P<0.05),GSH contents(P<0.01)and GSH/GSSG(P<0.05)were significantly decreased,the GSSG content(P<0.05)was increased;and plasma irisin and musclin levels were significantly decreased(P<0.05).After six weeks of aerobic exercise,the plasma TG(P<0.05),TC(P<0.01)and LDL-C(P<0.05)of atherosclerotic mice were significantly decreased,and the expression of the 4-HNE-modified protein and protein carbonyl in skeletal muscles were significantly decreased(P<0.05);the protein expressions of p-Nrf2(P<0.01),CAT(P<0.05),GPX1(P<0.05)and NQO1(P<0.05)were significantly increased;the mRNA expressions of Gss(P<0.05),Gsr(P<0.05),Gclc(P<0.05),Gclm(P<0.01)and GSH contents,the GSH/GSSG ratio(P<0.05)were increased;the mRNA expression of Fndc5(P<0.05),Acads(P<0.01),Hadha(P<0.01),Hadh(P<0.05),and the content of musclin in skeletal muscles(P<0.01),as the levels of irisin(P<0.01)and musclin(P<0.05)in the plasma were significantly increased.These results suggest that atherosclerosis reduces the antioxidant level and increases oxidative stress in skeletal muscles of mice,and six-week aerobic exercise activates the Nrf2 signaling pathway in skeletal muscles of atherosclerotic mice,which significantly improves oxidative damage of skeletal muscles.In addition,six weeks of aerobic exercise also effectively promoted the production of irisin,musclin and BAIBA in the skeletal muscles of atherosclerotic mice.