Fig. 1. Meteorin-like expression is reduced in aged muscle regeneration.

a Metrnl mRNA measured by qPCR from mouse TA muscles following BaCl₂-induced muscle damage (n = 6 independent animals/age/timepoint); two-tailed t test was used to compare young to old at each timepoint. b Metrnl mRNA and c plasma protein in young and old mice 24 h following downhill running-induced muscle damage (n = 6 independent animals/group); 2 × 2 ANOVA was used with Fisher’s LSD post hoc analysis. d Graphic representation of mouse downhill running experiments. e Circulating METRNL before and at 24 h post downhill running (n = 6 independent animals/group); 2 × 3 ANOVA was used with Fisher’s LSD post hoc analysis. f Circulating creatine kinase measure before and 72 h after injury. n = 6 independent animals/group; 2 × 2 ANOVA was used with Fisher’s LSD post hoc analysis. g Grip strength and h running time to fatigue as a percent of baseline measured before and each day following downhill running (n = 6 animals/group; two-tailed t test was used to compare old(Null) to old(Metrnl) at each timepoint. Source Data are provided as a source data file. Graphics created with BioRender.com. All p values are indicated with line connecting comparison groups. Data are presented as mean values ± SEM. WT wild-type, KO METRNL−/−, Y young, O old, ISO isochronic; HET heterochronic.