FIGURE 3.

Individual and grouped data showing the age‐related differences between Tph2 ^−/− and Tph2 ^+/+ mice on total oxygen consumption (VO₂) (a), total carbon dioxide production (VCO₂) (b), respiratory exchange ratio (RER) (e), and total motor activity (f) in light cycle and VO₂ (c), VCO₂ (d), RER (g), and total motor activity (h) in dark cycle. Younger—Tph2 ^+/+ (n = 5), Tph2 ^−/− (n = 5); Older—Tph2 ^+/+ (n = 5), Tph2 ^−/− (n = 5). Tph, tryptophan hydroxylase. **p < 0.01, ***p < 0.001 and ****p < 0.0001—effect of genotype using two‐way ANOVA. ## p < 0.01 and ###p < 0.001 effect of age using Two‐way ANOVA. †p < 0.05 Tukey's post hoc test in comparison with Tph2 ^+/+younger mice. ‡p < 0.05 Tukey's post hoc test in comparison with Younger—Tph2 ^+/+. ¶p < 0.05 Tukey's post hoc test in comparison with Younger—Tph2 ^−/− and Older—Tph ^+/+