Gynostemma pentaphyllum extract and Gypenoside L enhance skeletal muscle differentiation and mitochondrial metabolism by activating the PGC-1 alpha pathway in C2C12 myotubes

BACKGROUND/OBJECTIVES: Peroxisome proliferator-activated receptor-gamma co-activator-1 alpha (PGC-1 alpha) has a central role in regulating muscle differentiation and mitochondrial metabolism. PGC-1 alpha stimulates muscle growth and muscle fiber remodeling, concomitantly regulating lactate and lipid metabolism and promoting oxidative metabolism. Gynostemma pentaphyllum (Thumb.) has been widely employed as a traditional herbal medicine and possesses antioxidant, anti-obesity, anti-inflammatory, hypolipemic, hypoglycemic, and anticancer properties. We investigated whether G. pentaphyllum extract (GPE) and its active compound, gypenoside L (GL), affect muscle differentiation and mitochondrial metabolism via activation of the PGC-1 alpha pathway in murine C2C12 myoblast cells. MATERIALS/METHODS: C2C12 cells were treated with GPE and GL, and quantitative reverse transcription polymerase chain reaction and western blot were used to analyze the mRNA and protein expression levels. Myh1 was determined using immunocytochemistry. Mitochondrial reactive oxygen species generation was measured using the 2'7'-dichlorofluorescein diacetate assay. RESULTS: GPE and GL promoted the differentiation of myoblasts into myotubes and elevated mRNA and protein expression levels of Myh1 (type IIx). GPE and GL also significantly increased the mRNA expression levels of the PGC-1 alpha gene (Ppargc1a), lactate metabolism-regulatory genes (Esrra and Mct1), adipocyte-browning gene fibronectin type III domain-containing 5 gene (Fndc5), glycogen synthase gene (Gys), and lipid metabolism gene carnitine palmitoyltransferase 1b gene (Cpt1b). Moreover, GPE and GL induced the phosphorylation of AMP-activated protein kinase, p38, sirtuin1, and deacetylated PGC-1 alpha. We also observed that treatment with GPE and GL significantly stimulated the expression of genes associated with the anti-oxidative stress response, such as Ucp2, Ucp3, Nrf2, and Sod2. CONCLUSIONS: The results indicated that GPE and GL enhance exercise performance by promoting myotube differentiation and mitochondrial metabolism through the upregulation of PGC-1 alpha in C2C12 skeletal muscle.