Baicalin Promotes Skeletal Muscle Fiber Remodeling by Activating the p38MAPK/PGC-1α Signaling Pathway

Skeletal muscle is the major tissue for metabolic activity in the body and performs a variety of physiological functions. Among these, muscle fiber types are decisive in muscle function and meat quality. Numerous studies have shown that natural products can affect the development of skeletal muscle, regulate the formation of muscle fibers, and impact muscle function under physiological or pathological conditions. Baicalin, a natural flavonoid compound mainly derived from the dried roots of <i>Scutellaria baicalensis</i>, has been reported to affect glucose metabolism and insulin resistance in skeletal muscle. However, the role of baicalin in the conversion of skeletal muscle fiber types and its underlying mechanisms remain unclear. This study aimed to explore the effects of baicalin on skeletal muscle fiber conversion in vitro and in vivo. The in vitro experiment used C2C12 cells as a model, with a baicalin treatment concentration of 125 μM; the in vivo experiment used C57BL/6J mice and weaned piglets as the models. The results showed that baicalin could participate in the remodeling of skeletal muscle fibers, promoting the conversion from glycolytic fibers to oxidative fibers in mice and pigs. This was evidenced by increased protein and mRNA expression levels of genes related to oxidative fibers, upregulated SDH enzyme activity, and mitochondrial complex expression in vivo and in vitro, while the protein and mRNA expression levels of genes related to glycolytic fibers were decreased, and LDH enzyme activity was downregulated. Mechanistic studies revealed that baicalin, as a small molecule, could target and bind to the p38 MAPK protein, increase its expression and phosphorylation levels, and activate the p38 MAPK/PGC-1α signaling pathway. Collectively, these data showed that baicalin induced a shift in skeletal muscle fiber composition from glycolytic to oxidative myofibers by activating the p38 MAPK/PGC-1α signaling pathway, thereby affecting the meat quality.