Capsaicin mimics mechanical load-induced intracellular signaling events

Abstract

M echanical load-induced intracellu- lar signaling events are important for subsequent skeletal muscle hypertro- phy. We previously showed that load- induced activation of the cation channel TRPV1 caused an increase in intracellu- lar calcium concentrations ([Ca2+ ]i ) and that this activated mammalian target of rapamycin (mTOR) and promoted muscle hypertrophy. However, the link between mechanical load-induced intracellular signaling events, and the TRPV1-mediated increases in [Ca2+ ]i are not fully understood. Here we show that administration of the TRPV1 ago- nist, capsaicin, induces phosphorylation of mTOR, p70S6K, S6, Erk1/2 and p38 MAPK, but not Akt, AMPK or GSK3β. Furthermore, the TRPV1-induced phos- phorylation patterns resembled those induced by mechanical load. Our results continue to highlight the importance of TRPV1-mediated calcium signaling in load-induced intracellular signaling pathway