3周大运动量训练对大鼠骨骼肌mTOR信号通路的影响

The Characteristics of Skeletal Muscle Protein Synthesis during Three-week High Volume Training

目的:探讨3周大运动量训练过程中,大鼠骨骼肌蛋白合成代谢的变化规律和哺乳动物雷帕霉素靶蛋白(mTOR)信号通路的变化特点。方法:以7周龄雄性SD大鼠(36只)为研究对象,按体重随机分对照组3组(C1、C2、C3)和运动组(E1、E2、E3)3组。运动组进行3周大强度和中等强度相结合大运动量跑台训练,对照组不运动。每周训练结束后,随机选取对照组和运动组各1组,测试腓肠肌湿重、肌球蛋白重链(MHC)表达、mTOR及其下游信号70KD核糖体蛋白S6激酶(p70S6K)、真核起始因子4E结合蛋白1(4EBP1)的蛋白表达和磷酸化水平。结果:(1)第1周训练结束,与同期对照组(C1)相比,E1组p70S6K(Thr389)磷酸化水平和4EBP1蛋白表达显著升高(P<0.01);4EBP1(Thr37/46)磷酸化水平显著升高(P<0.05)。(2)第2周训练结束,与同期对照组(C2)相比,E2组mTOR(Ser2448)磷酸化水平显著降低(P<0.01);p70S6K(Thr389)磷酸化水平显著降低(P<0.05)。(3)第3周训练结束,与同期对照组(C3)相比,腓肠肌MHC蛋白表达显著降低,mTOR(Ser2448)和p70S6K(Thr389)磷酸化水平显著降低(P<0.01);腓肠肌湿重和mTOR、p70S6K、4EBP1蛋白表达显著降低(P<0.05)。结论:3周大运动量训练过程中,骨骼肌蛋白合成能力呈现出先升高后降低的变化特点。大运动量训练疲劳后对骨骼肌蛋白合成的抑制作用主要由m TOR信号通路蛋白表达降低所致。

Objective To explore the characteristics of skeletal muscle protein synthesis and mammalian target of rapamycin（mTOR） signaling pathways during three-week high volume training. Methods 7-week old SD rats were randomly divided into 3 sedentary control groups（C1,C2,and C3） and 3 exercise groups（E1,E2,and E3）. Rats in the exercise groups performed high volume training with high and moderate intensity for three weeks. At the end of each week training,the gastrocnemius wet weight,myosin heavy chain（MHC）,mTOR,70-k D S6 protein kinase（p70S6K）,e IF4E-binding protein 1（4EBP1）,and phosphorylation levels of m TOR（Ser2448）,p70S6K（Thr389）,and 4EBP1（Thr37/46） were determined respectively from groups E1,E2,and E3. Independent-samples t test was applied. Results（1）As compared with group C1,the phosphorylation level of p70S6K（Thr389）,4EBP1 total protein and 4EBP1（Thr37/46） in group E1 after the first week of training increased significantly（P〈0.01 and P〈0.05）.（2）As compared with group C2,the phosphorylation level of m TOR（Ser2448） and p70S6K（Thr389） in group E2 after the second week of training decreased significantly（P 〈0.01 and P 〈0.05）.（3）As compared with group C3,the gastrocnemius wet weight,m TOR,p70S6 K,4EBP1 total protein,MHC total protein,and m TOR（2448） and p70S6K（Thr389） in group E3 after the third week of training decreased significantly（P 〈0.05 and P 〈0.01）. Conclusion The ability of protein synthesis in skeletal muscle during the 3-week high volume training tended to increase at the beginning and decrease thereafter. Decreased protein synthesis ability induced by strenuous exercise mainly caused by the reduced protein expression of m TOR signaling pathway.