Extended Data Fig. 3: Details of 13C-glucose tracing experiments, inhibitors, depth profiling, and R1P fragmentation.
(a) Zoomed-in mass spectra obtained from 13C-labeled and control hippocampal slices. (b) Ion images of hippocampal slices that were unlabeled, labeled with 13C6 glucose (control) or labeled with 13C6 glucose and stimulated with 50 mM KCl for 5 min. (c) The relative contribution of each isotopologue in control or 5-min-KCl-stimulated DGs after 10 min (I) or 35 min (II) of 13C6 glucose labeling (n = 6 mice). Hypothesis testing was done by two-tailed, paired Student′s t-tests. P-values from left to right = 0.028, 0.036, 0.031, 0.004, 0.040. (d) The 6-phosphogluconate (6PG) levels in control and KCl stimulated DGs in absence or presence of G6PDi (50 µM) (n = 6 mice). (e) Inosine levels in control and KCl stimulated DGs in absence or presence of forodesine (Foro, 20 µM). (n = 6 mice). A two-sided t-test with multiple comparison correction was performed using the two-stage linear step-up procedure with Q = 1%. P-values from left to right bracket = 0.01, 0.049 (d); (top) 0.049, <0.001 (bottom), 0.003 (bottom). (f) Example spectrum of ribose 5-phosphate (R5P) and ribose 1-phosphate (R1P) and (g) chemical structure of R1P ([M-H]− m/z: 229.01) and its specific fragment ([M-H]− m/z: 211.00) detected in the multiple reaction monitoring strategy. (h) Average carbon atom labeling (atom%) of lower glycolytic intermediates throughout the depth of the hippocampal slice (n = 3 mice). All values are mean ± SEM. Significance is indicated as p < 0.001 (***), p < 0.01 (**), or p < 0.05 (*). GAP/DHAP = glyceraldehyde 3-phosphate/dihydroxyacetone phosphate; BPG = bisphosphoglycerates, PG = phosphoglycerates; PEP = phosphoenolpyruvate; 6PG = 6-phosphogluconate; PentoseP = pentose phosphates; S7P = sedoheptulose phosphates; E4P = erythrose 4-phosphate; PCr = Phosphocreatine, Cr = Creatine.
