Multilevel regulation of skeletal muscle ferroptosis in aging: sex- and exercise-dependent effects on histological, molecular, and genetic markers.

Ferroptosis, an iron-dependent form of regulated cell death, is increasingly recognized as a key contributor to aging-associated skeletal muscle degeneration and dysfunction. However, the interactive effects of aging, sex, and exercise modality on ferroptosis regulatory markers at the histological, protein, and gene expression levels remain poorly understood. Male (n = 23) and female (n = 23) mice aged 7 (young) and 17 (aged) months were assigned to sedentary control, voluntary wheel running, or forced treadmill exercise. Ferroptosis in the quadriceps muscle was assessed using histological markers (e.g., fibrosis, Fe3⁺ accumulation, 4-HNE, MDA), protein-level markers (e.g., GPX4, SLC7A11, p-AMPK, MDA, GSH/GSSG), and gene expression markers (e.g., SLC7A11, GSS, ACSL4, POR). Aging significantly elevated histological indicators of ferroptosis-fibrosis, lipid peroxidation, and iron overload-regardless of sex. At the protein and gene levels, sex-dependent differences were evident: aged females exhibited lower MDA and GSSG levels and upregulation of antioxidant-related genes, compared with aged males. Both exercise interventions modulated ferroptosis markers, with forced exercise exerting more pronounced effects than voluntary exercise. Notably, aged females demonstrated the most substantial reductions in ferroptosis-related markers in response to forced exercise, indicating a significant sex-by-exercise interaction. Aging markedly increases ferroptosis-related changes in skeletal muscle, with partial sex-specific differences at the molecular level. Forced exercise provides more robust regulatory effect against ferroptosis than voluntary exercise, especially in aged females. These findings underscore the therapeutic potential of sex-specific, targeted exercise interventions for mitigating ferroptosis-mediated muscle deterioration during aging.