Fig. 7: Myonectin administration improves muscle atrophy in SAMP8 and Mdx mice.

a–c Ad-myonectin (myonectin) or Ad-β-gal (control) was intra-muscularly injected into SAMP8 mice at the age of 33 weeks. At 4 weeks after treatment with myonectin or control, SAMP8 mice were sacrificed, and the gastrocnemius muscles were used for analysis. a Gastrocnemius muscle weight/body weight ratio of myonectin-treated or control-treated SAMP8 mice. N = 5 in SAMP8 mice before treatment. N = 7 in SAMP8 mice after myonectin or control treatment. b Upper left panels show representative images of muscle fibers from SAMP8 mice before treatment or after treatment with myonectin or control. Scale bars show 100 μm. Lower panels show quantification of mean cross sectional area (CSA) and CSA distribution of SAMP8 mice before treatment or after treatment with myonectin or control. N = 5 in each group. c Left panels show representative Western blot analyses of PGC1α, PGC1α4 and tubulin in SAMP8 mice before treatment or after treatment with myonectin or control. Right graphs show quantitative analyses of PGC1α/tubulin and PGC1α4/tubulin signal ratios. N = 5 in each group. d–f Ad-myonectin (myonectin) or Ad-β-gal (control) was injected into gastrocnemius muscles of mdx mice at the age of 4 weeks. At 4 weeks after treatment with myonectin or control, mdx mice were sacrificed. d Gastrocnemius muscle weight/body weight ratio of myonectin-treated or control-treated mdx mice. N = 5 in each group. e Upper panels show representative images of muscle fibers from myonectin-treated or control-treated mdx mice. Scale bars show 100 μm. Lower panels show quantitative analysis of mean CSA and CSA distribution of myonectin-treated or control-treated mdx mice. N = 5 in each group. f Left panels show representative Western blot analyses of PGC1α, PGC1α4 and tubulin. Right graphs show quantitative analyses of the PGC1α/tubulin and PGC1α4/tubulin signal ratios of myonectin-treated or control-treated mdx mice. N = 5 in each group. Data are presented as means ± SEM. One-way ANOVA with a post-hoc analysis for a–c. Two-tailed unpaired Student’s t-test for d–f. Gastroc. gastrocnemius muscle, BW body weight, SAMP8 senescence accelerated mouse prone 8, Ad-β-gal Adenoviral vectors containing the gene for β-galactosidase, Ad-myonectin Adenovirus vectors containing the gene for myonectin.