Sex differences in metabolic remodeling and skeletal muscle regeneration following cardiotoxin-induced injury

Skeletal muscle regeneration is a dynamic biological process that requires metabolic remodeling, satellite cell activation, inflammatory responses, and tissue remodeling. Although biological sex is recognized as an important determinant of skeletal muscle regeneration, whether males and females utilize distinct metabolic programs during regeneration remains poorly understood. In the present study, we investigated sex-dependent differences in metabolic remodeling and regenerative responses following cardiotoxin (CTX)-induced skeletal muscle injury in mice. Targeted metabolomic analysis performed at 7 days post-injury (DPI) revealed clear sex-dependent metabolic remodeling. Principal component analysis and pathway enrichment analysis identified glycolysis/gluconeogenesis as the most significantly altered metabolic pathway following injury. Male mice exhibited higher levels of several glycolytic, tricarboxylic acid (TCA) cycle, and amino acid metabolites than female mice. In contrast, female mice showed greater expression of Pax7, Myf5, and Myod1, together with increased Pax7-positive cells, greater Cyclin D1 staining, and higher expression of Ccne1, Cdc2, and Cdk4. Local inflammatory responses also differed between sexes, with distinct temporal patterns of MCP-1, IL-6, TNF-α, and CD45 during regeneration. Histological analyses demonstrated greater lipid accumulation in female muscle at 7 DPI, whereas both sexes exhibited comparable percentages of centrally nucleated fibers and similar restoration of muscle architecture by 21 DPI. Together, these findings indicate that biological sex is associated with differences in metabolism, satellite cell-associated responses, inflammatory responses, and tissue remodeling during skeletal muscle regeneration. Although males and females ultimately achieved comparable structural recovery, the regenerative process differed substantially during the early phase after injury. These findings provide additional insight into the biological processes underlying sex-dependent skeletal muscle regeneration and establish a foundation for future studies investigating the mechanisms linking metabolism to regeneration.