Diffusion-weighted NMR spectroscopy allows probing of 13C labeling of glutamate inside distinct metabolic compartments in the brain.
In the present work, diffusion-weighted (DW)-NMR spectroscopy of glutamate was performed during a (13)C-labeled glucose infusion in monkey brain (six experiments). It is shown that glutamate (13)C labeling occurs significantly faster at higher diffusion weightings-slightly for glutamate in position C4, and more markedly for glutamate in position C3. This demonstrates the existence of different diffusion compartments for glutamate, associated with different metabolic rates. Metabolic modeling of (13)C enrichment time-courses suggests that these compartments might be gray and white matter, each having a specific oxidative metabolism rate possibly paralleled by a specific glutamate diffusion coefficient.
Valette
Julien
J
CEA-NeuroSpin, Saclay, France. julien.valette@cea.fr
Chaumeil
Myriam
M
Guillermier
Martine
M
Bloch
Gilles
G
Hantraye
Philippe
P
Lebon
Vincent
V
D000465:Algorithms; D000818:Animals; D001921:Brain / Q000378:metabolism*; D002247:Carbon Isotopes / Q000032:analysis / Q000737:chemistry; D003198:Computer Simulation; D004058:Diffusion; D018698:Glutamic Acid / Q000032:analysis*; D007553:Isotope Labeling; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008657:Metabolic Clearance Rate; D008959:Models, Neurological; D015336:Molecular Probe Techniques
D002247:Carbon Isotopes; D018698:Glutamic Acid