【摘要】 目的:采用注射外源性IGF-I和一周跑台运动,观察对大鼠骨骼肌mTOR信号通路的影响,深入探讨IGF-I对运动骨骼肌适应性肥大的机理。方法:8周龄雄性SD大鼠在适应性训练后分为四组:安静组(S)、安静IGF-I组(SI)、运动组(E)、运动+IGF-I组(EI)。运动方式为跑台运动(20m/min,10%,60min/d),每天一次,共7天。外源性IGF-I为小腿后侧肌肉隆起处的皮下注射。用Western Blotting法检测腓肠肌MHC、PI3K、AKt、mTOR、p70S6K蛋白和Akt(Ser473)、mTOR(Ser2448)和p70S6K(Thr389)的磷酸化表达。结果:在一周后,外源性IGF-I显著促进骨骼肌MHC的表达,骨骼肌PI3K、Akt、mTOR蛋白和Akt(Ser473)、mTOR(Ser2448)和p70S6K(Thr389)的磷酸化表达显著增强。运动显著促进mTOR蛋白和Akt(Ser473)、mTOR(Ser2448)和p70S6K(Thr389)磷酸化的表达。对运动的反应,上述信号的磷酸化表达高于蛋白表达。结论:1)一周外源性IGF-I注射明显促进运动骨骼肌mTOR通路的活性;而1周跑台运动与IGF-I具有协同增强效应。2)在运动和注射外源性IGF-I的刺激下,mTOR通路各信号分子的磷酸化表达比蛋白表达更为敏感。建议今后对信号的研究以检测信号分子的磷酸化表达为主。更多还原

【Abstract】 Objective:the purpose of this study was to examine the effect of mTOR signal pathway on Skeletal Muscle Adaptive Hypertrophy in resistance treadmill exercise model through injecting exogenous IGF-I in vivo.Methods:adult male Sprague-Dawley rats(8 weeks old) were randomly divided into 4 groups after adaptive training:sedentary(S),IGF-I group(SI),exercise group(E) and IGF-I plus exercise group(EI).The following treadmill training was applied:20m/min at 10% slope,60 min;once per day,7 days.Rats were treated daily with exogenous IGF-I(5.5 mg/kg,diluted with saline) or saline local subcutaneously for 7 days.The MHC,PI3K,AKt and phosphorylation of Akt(Ser473),mammalian target of rapamycin(mTOR) and phosphorylation of mTOR(Ser2448),p70(S6K) and phosphorylation of p70(S6K)(Thr 389) of gastrocnemius muscle were determined by Western blotting.Results:After 1 week,wet weight and MHC of gastrocnemius muscle was promoted significantly by IGF-I,PI3K,AKt and phosphorylation of Akt(Ser473),mTOR and phosphorylation of mTOR(Ser2448),p70(S6K) and phosphorylation of p70(S6K)(Thr 389)were significantly promoted by IGF-I,and but they were elevated by exercise except PI3K.Conclusions:These results suggest that:1) The mTOR pathway of skeletal muscle was significantly promoted by exogenous IGF-I,and the positive effect was global.Exercise had synergy effect with exogenous IGF-I in vivo,while exercise can synergy improve mTOR pathway with IGF-I.The effect of exercise was particular emphasis on partial elements of mTOR pathway.2) Phosphorylations of mTOR pathway were sensitive than total-molecules.更多还原