Figure 6. RJx-01 protects the skeletal muscle ultrastructure and mitochondrial morphology in aged mice.

(A) Oxygen consumption (VO₂), carbon dioxide production (VCO₂), and energy expenditure (EE) in aged mice treated with RJx-01 for 10 weeks (Untreated, n = 8; RJx-01, n = 4). (B–D) Representative electron micrographs of EDL muscles of aged mice treated with and without RJx-01. (B) Arrows represent sarcomere misalignment. Scale bar: 2 µm. (C) The arrow denotes less electron-dense matrix mitochondria. (D) The arrow points to a swollen mitochondrion. Different magnifications are shown. Scale bars: 500 nm. (E) Number of damaged mitochondria in EDL muscle of untreated and RJx-01–treated mice (number of mitochondria analyzed per mouse, 209–288) (Untreated, n = 3; RJx-01, n = 4). (F) Serum FGF21 and urine GDF15 levels (Untreated, n = 9; RJx-01, n = 6). Data are shown as mean ± SEM. *P < 0.05; **P < 0.01; ***P < 0.001 by 2-tailed Student’s t test.