1周跑台运动对大鼠骨骼肌mTOR信号通路的影响

Effects of One Week Treadmill Exercise on mTOR Pathway of Rats′ Skeletal Muscle

目的通过观察1周跑台运动对整个mTOR信号通路的影响,以深入探讨运动训练中蛋白合成信号的变化特点。方法雄性SD大鼠在适应性训练后随机分为安静组(S组)和运动组(E组),每组6只。运动方式为跑台(20 m/min,坡度10%,1 h/天,共7天)。Western blot检测腓肠肌PI3K、Akt、mTOR、p70S6K和4EBP1蛋白表达,及Akt(Ser473)、mTOR(Ser2448)、p70S6K(Thr389)和4E-BP1(Thr37/46)磷酸化表达。结果大鼠在1周跑台运动后,E组的mTOR信号通路表达均高于S组。运动显著促进了Akt(Ser473)(P<0.01)、mTOR(Ser2448)(P<0.05)、p70S6K(Thr389)(P<0.01)和4EBP1(Thr37/46)(P<0.01)的磷酸化表达及4EBP1(P<0.05)的蛋白表达,分别是S组的127%、113%、122%、134%和116%。结论适量抗阻运动增强mTOR通路的表达,且下游信号的变化幅度明显大于上游信号;运动对mTOR通路的影响中,各信号分子生物活性的增强表现得更为明显;mTOR通路中一些信号分子的磷酸化状态对运动训练的反应更为敏感,可以用来作为运动对mTOR通路影响的标志物。

Objeetive The purpose of this study was to examine the regulatory mechanism of exercise on muscle protein synthesis through entire mTOR pathway after one week treadmill exercise. Methods Adult male Sprague - Dawley rats （8 weeks old） were randomly divided into 2 groups after adaptive training： by name, sedentary group（S） and exercise group （E）. The following treadmill training method was applied：20 m/min at 10% slope, 60 min; once per day, 7 days. The total of PI3K, Akt, mammalian target of rapamycin （mTOR）, 70 - kDa ribosomal protein S6 kinase （p70S6K） , eIF4E binding protein 1 （4EBP1） and phosphorylation of Akt （ Ser473 ）, mTOR （ Ser2448 ）, p70S6K （ Thr389 ）, 4EBP1 （ Thr 37/46 ） of gastrocnemius muscle were determined by Western blotting. Results After one week, mTOR pathway was significantly elevated by exercise. Akt （Ser473） （P〈0.01）, mTOR （Ser2448） （P〈0.05）, p70S6K （Thr389） （P〈0.01）, 4EBP1 （Thr37/ 46） （ P 〈 0.01 ） phospborylation and total - 4EBPI （ P 〈 0.05 ） of E were significantly higher than S （ 27%, 13 %, 22%, 34% and 16% , respectively ）. Conclusions These results show that： 1 ） Exercise could elevate mTOR pathway of skeletal muscle, and the changing magnitude of downstream of roTOR pathway was significantly higher than that of upstream. 2） During these changes of mTOR pathway by exercise, the biological activity underwent a more significant change. 3 ） Phosphorylation of some component of mTOR pathway was more sensitive to exercise, and they could be employed as biologic markers to monitor effect of exercise upon skeletal muscle protein synthesis.