Figure 4

L-158809 improved muscle regeneration, body weight, locomotion, and muscle strength in dy^W/dy^Wmice. (A) L-158809 (dy^W-L158) did not significantly affect the number of centrally nucleated fibers (CNF) in either triceps or diaphragm muscle of dy^W/dy^Wmice (n ≥ 4). (B) Staining of diaphragm muscle for the regeneration marker developmental myosin heavy chain (dMyHC; green), the basement membrane marker laminin-γ1 (red), and the nuclear marker 4",6"-diamidino-2-phenylindole hydrochloride (DAPI) (blue). L-158809 enabled damaged dy^W/dy^Wmuscle fibers to regenerate, whereas in non-treated dy^W/dy^Wmuscle many dMyHC-expressing cells continued degenerating. (C) L-158809 application strongly increased the number of intact regenerating muscle fibers in dy^W/dy^Wmice (n ≥ 4). (D) Tibialis anterior (TA) muscle stained for dMyHC (green), laminin-γ1 (red), and DAPI four days after notexin-induced injury. L-158809 increased the regenerative capacity of damaged dy^W/dy^Wmuscle. (E) The number of dMyHC-expressing fibers in TA muscle of dy^W/dy^Wmice 5 days after notexin injection was more than 8 times higher in L-158809 treated dy^W/dy^Wmice but was still lower than in controls (n = 3). (F) L-158809 increased the average body weight of dy^W/dy^Wmice from 7.6 g to 9.5 g, although age-matched wild-type (WT) mice weigh more than 20 g. (n ≥ 12). (G). L-158809 doubled the time a dy^W/dy^Wmouse could hold itself on a vertical grid, from 26 seconds to 51 seconds (P = 0.0001) (n ≥ 14). (H) L-158809 increased the time dy^W/dy^Wmice explored an unknown surrounding (P = 0.0004) within 10 minutes (n ≥ 12). All values represent the mean ± SEM (n ≥ 4). One-way ANOVA: **P ≤ 0.001; * P ≤ 0.05; n.s. (non-significant) P > 0.05. Scale bar = 50 μm, if not indicated differently.