Effects of transient receptor potential channel activation during myogenic progression and skeletal muscle function during voluntary exercise.

Capsaicin and menthol, agonists of transient receptor potential channels, are known to influence energy metabolism. However, their roles in skeletal muscle function are unclear. Therefore, this study aimed to investigate the effects of capsaicin and menthol on skeletal muscle differentiation and muscle quality. In vitro, capsaicin and menthol increased myosin heavy chain (MYH)4 expression, while menthol upregulated MYH1. Both compounds reduced MYH2 and MYH7 levels. Additionally, capsaicin enhanced uncoupling protein (UCP)3 expression, and menthol increased UCP2, UCP3, and M-type creatine kinase. In vivo, topical application during voluntary running did not affect body or muscle mass, but capsaicin reduced fat mass and increased locomotor activity. Menthol enhanced light-phase activity. Both treatments elevated MYH4, UCP2, and UCP3 in muscle, and suppressed myostatin expression. These findings suggest capsaicin and menthol modulate skeletal muscle phenotype and metabolism through both direct cellular effects and increased physical activity.