Localized in vivo ¹H NMR detection of neurotransmitter labeling in rat brain during infusion of [1-¹³C] D-glucose

Resolved localized nuclear magnetic resonance (NMR) signals of ¹H bound to ¹³C label in the carbon positions of glutamate C4, C3 and glutamine C4, C3, as well as in aspartate C3, lactate C3, alanine C3, γ,-aminobutyric acid C3, and glucose C1 were simultaneously observed in spectra obtained from rat brain in vivo. Time-resolved label incorporation was measured with a new adiabatic carbon editing and decoupling (ACED) single-voxel stimulated echo acquistion mode (STEAM) sequence. Adiabatic carbon broadband decoupling of 12 kHz bandwidth was achieved in vivo, which decoupled the entire ¹³C spectrum at 9.4 T. Resonances from N-acetyl-aspartate and creatine were also detected, consistent with natural-abundance ¹³C levels. These results emphasize the potential of ¹H NMR for following complex biochemical pathways in localized areas of resting rat brain as well as during focal activation using infusions of ¹³C-labeled glucose.