Figure 1. Plasma MOTS-c levels decrease and skeletal muscle levels increase with aging. Plasma MOTS-c (A), correlated with HOMA-IR (B), fat mass (C), lean mass (D), and muscle MOTS-c expression (E) in young, middle-aged and older males. Representative blots are independent and from different participants. Correlation between plasma MOTS-c and muscle MOTS-c expression in young (F), middle (G), and combined (H). Significance was determined using linear regression or one-way ANOVA. Data is presented as means ± SE, n=26 per group except for body composition measurements where data was not available for a young (n=25) and middle-aged (n=25) participant. *p<0.05, **p<0.01, ***p<0.001.