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Arginine induces skeletal muscle fiber type conversion by upregulating Akirin2 and AMPK/PGC-1α in mice

We have previously reported that arginine promotes slow myosin heavy chain expression in cell culture via Akirin2 and the AMP-activated protein kinase (AMPK) signaling pathway. Our goal in the present study was to investigate whether arginine has similar functions and molecular mechanisms in vivo. Kunming mice were fed a diet supplemented with arginine and actively immunized with Akirin2. The study lasted for 40 d. Tibialis anterior (TA) muscle was harvested for analysis. We found that Kunming mice supplemented with arginine significantly increased the oxidative fibers expression and decreased the expression of glycolytic fiber. Expressions of peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) and AMPK were increased in the TA muscle of arginine-treated Kunming mice. We also find that dietary supplementation of arginine increased the succinate dehydrogenase and malate dehydrogenase activities and decreased the lactate dehydrogenase activity. But active immunization against Akirin2 got opposite results. These results indicated that arginine induced muscle fiber transition from type II to type I, which may be mediated by Akirin2 and AMPK//PGC-1α signaling pathway.