Changes in palmitate- and stearate-containing glycerophospholipids in skeletal muscle during clenbuterol-induced fast-twitch fiber transition and hypertrophy.

Fast- and slow-twitch skeletal muscle fibers exhibit distinct glycerophospholipid compositions, and slow-twitch transition is accompanied by characteristic changes in glycerophospholipid molecular species. However, whether glycerophospholipid composition is remodeled during fast-twitch fiber transition and skeletal muscle hypertrophy remains unclear. In this study, we examined changes in palmitate- and stearate-containing glycerophospholipids using a mouse model of clenbuterol-induced fast-twitch transition and hypertrophy. Clenbuterol administration increased the proportion of fast-twitch fibers and induced skeletal muscle hypertrophy. Lipidomic analysis revealed a significant increase in palmitate-containing phosphatidylcholine and a decrease in stearate-containing phosphatidylcholine in the tibialis anterior and soleus muscles. Consistent with these glycerophospholipid alterations, the expression of several acyltransferases, such as glycerol-3-phosphate acyltransferase 3 (GPAT3), involved in glycerophospholipid acyl-chain determination was significantly altered. These findings demonstrate that glycerophospholipid composition is remodeled during fast-twitch fiber transition and muscle hypertrophy, highlighting lipid remodeling as a component of skeletal muscle phenotypic adaptation.