Ginsenoside Rg3 upregulates myotube formation and mitochondrial function, thereby protecting myotube atrophy induced by tumor necrosis factor-alpha

Edumpharmacological relevance: Ginsenoside Rg3 from Panax ginseng has reported to have multiple pharmacological activities including anti-diabetics, anti-inflammation and anti-cancer. However, the effect of ginsenoside Rg3 on myogenic differentiation and muscle atrophy is unknown. Aim to the study: In this study, we investigated the myogenic effect and underlying molecular mechanisms of ginsenoside Rg3 on myotube atrophy induced by tumor necrosis factor-alpha (TNF-alpha). Materials and methods: C2C12 myoblasts were induced to differentiate for one day followed by the treatment of TNF-alpha along with vehicle or ginsenoside Rg3 for additional 2 days and subjected to immunoblotting, immunocytochemistry, quantitative RT-PCR and biochemical analysis for mitochondrial function. Results: Ginsenoside Rg3 promotes myogenic differentiation and multinucleated myotube formation through Akt activation in a dose-dependent manner, without any cytotoxicity. Ginsenoside Rg3 treatment restores myotube formation and increases myotube diameters under TNF-alpha-treated conditions. Ginsenoside Rg3 enhances Akt/mTOR (mammalian target of rapamycin) signaling that in turn stimulates muscle-specific gene expression such as myosin heavy chain (MHC) and Myogenin, and suppresses the expression of muscle-specific ubiquitin ligases. In addition, ginsenoside Rg3 in TNF-alpha-treated myotubes significantly inhibits the production of mitochondrial ROS and restores mitochondrial membrane potential (MMP) and ATP contents. Furthermore, ginsenoside Rg3 upregulates the activities and expression of peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PGC1 alpha) and the mitochondrial biogenetic transcription factors, nuclear respiratory factor-1 (NRF1) and mitochondrial transcription factor A (Tfam) in TNF-alpha-induced myotube atrophy. Conclusions: This study provides a mechanistic insight into the effect of ginsenoside Rg3 on myogenic differentiation and myotube atrophy, suggesting that ginsenoside Rg3 has a promising potential as a therapeutic or neutraceutical remedy to intervene muscle weakness and atrophy.