ANALYSIS OF [1-C-13]D-GLUCOSE METABOLISM IN CULTURED ASTROCYTES AND NEURONS USING NUCLEAR-MAGNETIC-RESONANCE SPECTROSCOPY

The metabolism of [1-C-13]D-glucose by astrocytes, neurons and mixed astroglial/neuronal cultures derived from the striatum of fetal rats was studied using NMR. Metabolic activity was studied in resting and depolarized cells (55 mM K+), with dibutyryl cyclic-AMP added to the medium to promote cell differentiation, and with glutamate (0.1 mM) included in the medium. Due to sample limitations the accumulation of C-13 label in metabolites within the cells was not sufficient to quantitate. Of the metabolites released into the medium by the astrocyte cultures and the mixed astroglial/neuronal cultures, measurable amounts of label were present in lactate C-3 and C-2, glutamine C-2, C-3 and C-4, acetate C-2, citrate C-2 or C-4 and C-3, glycerol C-1 or C-3, succinate C-2 or C-3 and several unidentified metabolites. Of the labeled metabolites released into the medium, only succinate was markedly affected by K+-induced depolarization, dBcAMP, or glutamate. The label in succinate was increased, especially in the K+-depolarized astrocyte cultures (3- to 6-fold). The neuronal cultures consumed [1-C-13]D-glucose much more slowly than the astrocyte cultures or the mixed cultures. Except for lactate C-3, there was no measurable C-13 in metabolites in the medium of the neuronal cultures.