Effect of resistance training on mTOR and P70S6K Signaling pathway in skeletal muscle of rats

  Elucidating cell signaling mechanisms involved in muscle hypertrophy is one of the challenges of sport biologists. The mammalian target of Rapamycin (mTOR) is the most important factor in this process that regulated through phosphorylated the ribosomal protein S6 kinase of 70 kDa (p70S6K) and
increases protein synthesis in skeletal muscle. The purpose of this study was to determine the effect of resistance training (RT) on total (TmTOR) and phosphorylated (PmTOR) mTOR protein content and total (TP70) and phosphorylated p70s6k (PhP70) protein content, as markers of hypertrophy regulation in flexor hallucis longus (FHL) in normal male rats undergoing RT. For this purpose, 12 male Sprague Dawley rats were randomly divided into control (6 = n) and RT (6 = n). The RT consisted of climbing a ladder carrying a load suspended from the tail for 8 weeks (5 session week). The load of training was progressively changed 30- 200 % of subject's bodyweight. To investigate muscle samples, 48 hour after the last training session, FHL muscle was removed while animals were anestheitized. TmTOR, PmTOR, TP70PC and PhP70PC was measured by ELISA in muscle extract. One-way ANNOVA was used. The results showed RT muscle had a significantly greater Pour and p70s6k (P=0.001) (P=0.04).but no significant difference in TmTOR and p70s6k (p=0.421) (p=0.94). Totally, these findings, demonstrate that RT causes hypertrophy with increased phosphorylation of mTOR and p70s6k fitted.