Figure 4.

The HP [1-¹³C] lactate-to-pyruvate ratio is sensitive to modulation of microglia/macrophages status following TBI. (A) Representative heatmaps of the HP [1-¹³C] lactate-to-pyruvate ratios and corresponding HP ¹³C spectra showing increased HP [1-¹³C] lactate-to-pyruvate ratio and increased HP [1-¹³C] lactate production at 7d post-injury in the mouse that received the control diet but not in the mouse that received the PLX5622 diet. (B) Quantitative analyses of the HP [1-¹³C] lactate-to-pyruvate ratios revealed no significant differences between the injured and contralateral hemispheres of microglia depleted mice (Two-Way ANOVA, p = 0.089 for hemisphere effect, p = 0.1804 for time effect, p = 0.2792 for hemisphere and time interaction) at 7 days post-injury, contrasting with the increase of HP [1-¹³C] lactate-to-pyruvate ratio observed in mice that received the control diet (p = 0.0001). (C) HP [1-¹³C] lactate-to-pyruvate ratio, expressed as a percent change of the contralateral hemisphere, showed no change of the HP [1-¹³C] lactate-to-pyruvate ratio at 7 d post-injury compared to Baseline in mice that received the PLX5622, in contrast with the 37 ± 2% at 7 d (p < 0.0001) in mice that received the control diet. (D) PDH activity was decreased in the injured hemisphere of mice that received a control diet (p = 0.0011) but not in mice that received PLX5622 diet (p = 0.9429). (E) LDH activity remained unchanged (p = 0.1769). All values are reported as mean ± sem (n = 5–10 mice per group).