Introduction: 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.
Methodology: 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 body weight.
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.
Results: The results showed RT muscle had a significantly greater Pour and p70s6k (P=0.001) (P=0.04), but it caused no significant difference in TmTOR and p70s6k (p=0.421) (p=0/94).
Discussion: Findings demonstrate that RT causes hypertrophy with increased phosphorylation of mTOR and p70s6k fitted. The most important finding of this study was 37% increase phosphoryle p70s6k and it should be mentioned that p70s6k is phosphoryle and inhibited Threonine 229, Serin 404 and 411 by AMPK and Rapamaycin but to be activated, it should be phosphoryle in Threonine 389 by mTOR. In fact, to determine the signaling pathway causes these effects it is necessary to do more comprehensive studies with blocking different pathways.