Figure 3.

Phosphofructokinase 1 is inhibited in glycolytic muscle and glucose is rerouted toward glycogen stores

1. Enzymatic activity of phosphofructokinase in whole tibialis anterior muscle cytosolic homogenates is expressed as mean fold change ± SEM from age-matched WT at 65 days of age *P = 0.016 (WT n = 6, SOD1^G86R n = 7) and 105 days of age ***P < 0.0001 (n = 5/genotype), two-way ANOVA followed by Fisher's LSD post hoc test. Data shown are representative of two independent experiments having similar results.
2. Pyruvate was measured in whole tibialis anterior muscle tissue homogenates. The mean fold change ± SEM compared to age-matched WT are represented with *P = 0.019 at 65 days of age (n = 5/genotype) and *P = 0.041 at 105 days of age (n = 4/genotype), two-way ANOVA followed by Fisher's LSD post hoc test. Data shown are representative of two independent experiments having similar results.
3. Left: Representative Western blot showing glycogen synthase and phosphorylated glycogen synthase levels. Right: Quantification represents the mean ratio of optical densities of glycogen synthase/P-glycogen synthase ± SEM. At 65 days of age n = 6/genotype, *P = 0.0162, and at 105 days of age n = 5/genotype, *P = 0.0163, two-way ANOVA followed by Fisher's LSD post hoc test.
4. Left: Representative microphotographs of PAS staining from WT and SOD1^G86R tibialis anterior cross-sections at 65 and 105 days of age showing glycogen-negative (light pink) and glycogen-positive (dark pink) fibers. Scale bar: 200 μm. Right: Quantification of glycogen-negative (−) and glycogen-positive (+) fibers at 65 and 105 days of age. For (−) fibers: **P-values versus WT: 0.0026 at 65 days and 0.0074 at 105 days, for (+) fibers: ^##P-values versus WT: 0.0025 at 65 days and 0.0073 at 105 days (n = 5/genotype at 65 days and n = 4/genotype at 105 days, two-way ANOVA followed by Fisher's LSD post hoc test).