Figure 9.

Weekly versus daily prednisone induces divergent effects on myogenic and adipogenic capacities in Sgcg-null muscles. A: Real-time quantitative PCR on quadriceps muscle tissue showed up-regulation of the myogenic factor Mef2C after weekly prednisone, and its down-regulation after daily prednisone. B: Immunostaining of differentiated primary myoblasts (passage 0) showed that, after weekly prednisone, myoblasts increased fusion efficiency in multinucleated myotubes. Daily prednisone induced the opposite effects. C: The adipogenic factor Pparg was up-regulated in muscle after daily prednisone dosing. D: Daily prednisone dosing also associated with an increase in spontaneous adipocyte production by proliferating primary fibroadipogenic progenitors (FAPs), as demonstrated by Oil Red O staining of lipid-storing cells (left panels show representative images; right panel, quantitation). Data are expressed as means ± SEM and single mouse values (histograms) or Tukey distribution (box plots). n = 5 mice per group (3 males and 2 females per group). ^∗P < 0.05 versus vehicle (one-way analysis of variance test with Bonferroni multiple comparison). Scale bar = 100 μm (B and D, left panels). AU, arbitrary unit.