Fig. 3: The positive effects of fluoxetine on the stages of in vitro myogenesis are serotonin dependent and act through the 5-HT1B receptor.
From: Serotonin reuptake inhibitors improve muscle stem cell function and muscle regeneration in male mice
a Relative level of protein expressions of various 5-HT receptors in TA muscle from control and fluoxetine (FLX)-treated C57Bl6 mice (n = 5 per condition, p = 0.0317). b Representative western blot of the expressions of the targeted 5-HT1B receptor protein and the housekeeping GAPDH protein in C2C12 and murine primary myoblasts isolated by pre-platting from control mice (n = 3). Quantification of the relative number of (c) GFP+ (%) and (d) myogenin+ (%) among SCs exposed to FLX, FLX + GR127935 or GR127935 (5-HT1B antagonist) for 4 days (n = 7 per condition, p = 0.0011, p = 0.0085, p = 0.0027 for (d); p = 0.0019, p = 0.0294, p = 0.0004 for (e), respectively). Quantification of (e) the fusion index (%) and (f) the relative number of GFP+ (%) among SCs exposed to FLX, FLX + GR127935 or GR127935 for 14 days (n = 7 per condition, p = 0.0007, p = 0.0058, p = 0.0002 for (f), p < 0.0001 for (g), respectively). g Cell distribution (%) of GFP+ and myogenin+ among SCs from single fibers of Tg:Pax7nGFP mice exposed to 5-HT for 4 days (n = 4 per condition, p = 0.0473). h Representative immunostaining of SCs from single fiber at 4 days post plating; sections display GFP (green), Myogenin (red), Hoechst (nuclei, blue), the arrows indicate SCs. Scale bars indicate 20 µm. i First cell division and (j) cell division rate assessed by live videomicroscopy from SCs plated for 5 days with control serum, FLX serum or FLX serum+GR127935 (n = 4 per condition, p = 0.0458, p = 0.0402 for (j); p = 0.0230 for (k), respectively). k Quantification of the relative number of myogenin+ (%) among SCs plated for 4 days with control serum, FLX serum or FLX serum + GR127935 (n = 4 per condition, p = 0.0881, p = 0.0138). l Quantification of the relative number of Pax7+ (%) among SCs plated for 14 days with control serum, FLX serum or FLX serum+GR127935 (n = 4 per condition, p = 0.0261, p = 0.0448). For figures (c)–(f) and (i)–(l), SCs were sorted by FACS from Tg:Pax7nGFP mice. All values are represented as median with interquartile range. The two-tailed Mann–Whitney test for (a), the two-tailed Fisher’s test for (g) and the Kruskal-Wallis test for (c)–(f), (i)–(l). *p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001, ****p ≤ 0.0001. Source data are provided as a Source Data file.
