大强度耐力运动抑制骨骼肌线粒体的生物合成

High-intensity endurance exercise inhibits mitochondrial biogenesis in the skeletal muscle

背景:耐力运动对骨骼肌线粒体生成影响的研究多采用中小强度,长期大强度对其有何影响还不清楚,这种影响是否涉及5’-一磷酸腺苷激活的蛋白激酶(AMPK)、沉默信息调节因子2相关酶1(SIRT1)等调节线粒体生成的信号分子也未见报道。目的:观察AMPK/SIRT1信号级联在7周不同强度耐力运动中对骨骼肌线粒体生物合成的影响。方法:42只雄性SD大鼠分为安静组、中等强度运动组和大强度运动组。运动负荷为中等强度组28 m/min,60 min/d、大强度组38 m/min,60 min/d,每周运动5 d,休息2 d,共7周。运动组动物分别在运动后即刻、6 h和24 h取材。荧光定量PCR检测骨骼肌PGC-1α、SIRT1基因表达,Western blot测定P-AMPK、SIRT1蛋白表达。结果与结论:①中等强度运动后即刻、6 h、24 h,骨骼肌PGC-1αmR NA表达分别为安静组的362%(P<0.01)、657%(P<0.01)、116%,P-AMPK蛋白表达分别为安静组的112%、163%(P<0.05)、129%(P<0.05),SIRT1蛋白和mR NA表达分别为安静组的55%(P<0.05)、86%、103%和109%、155%(P<0.05)、132%(P<0.05)。②大强度运动后即刻、6 h、24 h,骨骼肌PGC-1αmR NA表达分别为安静组的274%(P<0.01)、130%(P<0.05)、68%(P<0.05),P-AMPK蛋白表达分别为安静组的235%(P<0.01)、166%(P<0.05)、160%(P<0.05),SIRT1蛋白和mR NA表达分别为安静组的199%(P<0.01)、166%(P<0.05)、164%(P<0.05)和255%(P<0.01)、292%(P<0.01)、122%。结果表明:①7周中等强度耐力运动显著增加骨骼肌PGC-1α基因表达,其机制可能涉及AMPK/SIRT1信号级联。②7周大强度耐力运动造成骨骼肌PGC-1α基因表达在运动后24 h时被抑制,这一过程是以非AMPK/SIRT1信号级联依赖性方式进行的。

BACKGROUND：There are many reports on the effects of low-to-moderate intensity endurance exercise on mitochondrial biogenesis in the skeletal muscle, but there is no understanding about the high-intensity endurance exercise. It has not been reported whether the high-intensity endurance exercise influence the mitochondrial biogenesis in the skeletal muscle through 5′-adenosine monophosphate-activated protein kinase （AMPK）/silent information regulator factor 2 related enzyme 1 （SIRT1） signal molecules. OBJECTIVE： To investigate the effect of AMPK/SIRT1 signaling cascade on the mitochondrial biogenesis in the skeletal muscle during different intensities of endurance exercises. METHODS：Forty-two male Sprague-Dawley rats were randomly divided into sedentary group, moderate-intensity exercise group and high-intensity exercise group. Moderate-intensity exercise load was 28 m/min, 60 min/d;high-intensity exercise load was 38 m/min, 60 min/d. In both exercise groups, the rats had 5 days of exercise and 2 days of rest within 1 week, and the exercise lasted for totaly 7 weeks. The animals of exercise groups were kiled immediately, 6 hours and 24 hours after exercise. Quantitative PCR was used to detect peroxisome proliferators γ activated receptor coativator-1α （PGC-1α） and SIRT1 gene expression, and western blot to detect phosphorylated-AMPK （P-AMPK） and SIRT1 protein expression. RESULTS AND CONCLUSION：（1） Immediately, 6 hours, 24 hours after moderate-intensity exercise, PGC-1α mRNA expression in the skeletal muscle was 362% （P 〈 0.01）, 675% （P 〈 0.01） and 116% of that in the sedentary group, P-AMPK protein expression was 112%, 165% （P 〈 0.05）, 129% （P 〈 0.05） of that in the sedentary group, the expressions of SIRT1 protein and mRNA were 55% （P 〈 0.05）, 86%, 103% and 109% （P 〈 0.05）, 155%, 132% （P 〈 0.05） of those in the the sedentary group, respectively. （2） Immediately, 6 hours, 24 hours after high-intensity exercise, PGC-1α mRNA expression in the skeletal muscle was 274% （P 〈 0.01）, 130% （P 〈 0.05）, 68% （P 〈 0.05） of that in the sedentary group, the expression of P-AMPK protein was 235% （P 〈 0.01）, 166% （P 〈 0.05）, 160% （P 〈 0.05） of that in the sedentary group, the expressions of SIRT1 protein and mRNA were 199% （P 〈 0.01）, 166% （P 〈 0.05）, 164% （P 〈 0.05） and 255% （P 〈 0.01）, 292% （P 〈 0.01）, 122% of those in the sedentary group, respectively. These findings indicate that （1） 7 weeks of moderate-intensity endurance exercise significantly increased PGC-1α gene expression in the skeletal muscle, and its mechanism may involve AMPK/SIRT1 signaling cascade; （2） 7 weeks of high-intensity endurance exercise significantly inhibited PGC-1α gene expression at 24 hours after exercise,and this process was carried out in an AMPK/SIRT1 signal cascade independent manner.