Fig. 6

Glycolytic proteins are downregulated in aged mice, which also shows less flexibility to the diet. a Scatter plot for proteomic targets involved in glucose metabolism (glycolysis, pentose phosphate pathway and glycogen metabolism) measured in quadriceps samples. Each dot represents the mean value of a specific protein on the HFD (y-axis) vs the LFD (x-axis). Prior to plotting, the levels of each protein were normalized to the average value of the same protein in all animals. Proteins along the dashed line are not regulated by the diet (mean LFD = mean HFD), while proteins above or below the line are up- or downregulated, respectively, by the HFD. PFKM, phosphofructokinase, muscle type; UGP2, UDP-glucose pyrophosphorylase 2; PGAM2, phosphoglycerate mutase 2; ENO3, enolase 3 (muscle isoform); ENO1, enolase 1; PGK1, phosphoglycerate kinase 1; PGM1/2, phosphoglucomutase isoforms 1 and 2; PKM1, pyruvate kinase, muscle isoform. b Simplified glycolysis scheme. The depicted values represent the % deviation from the average of the 4 groups (young/old and LFD/HFD) for each protein. The values are shown for old animals (panel on the left) and young animals (right panel). c, d Hexokinase and pyruvate kinase activities measured in quadriceps homogenates. Data are shown as mean ± SEM and were analysed using two-way ANOVA and multiple comparisons were performed using Tukey’s correction, n = 5–6 (young groups) or 10 (old groups), ^###p < 0.001 (old vs young), ^##p < 0.01 (old vs young), ^#p < 0.05 (old vs young), matched diets, ***p < 0.001 (LFD vs HFD), **p < 0.01 (LFD vs HFD), *p < 0.05 (LFD vs HFD), matched ages. Supporting data values can be found in Additional file 10 and proteomics dataset in Additional files 4 and 5.