BRAIN GLUCOSE METABOLISM BY 13C NMR

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APPLICANT'S ABSTRACT: The effects of ethanol on the glutamate and gamma amino butyric acid (GABA) neurotransmitter systems, and behavioral responses involving these systems, are well established. Less is known of the influence of ethanol on the rates of synthesis of the amino acid neurotransmitters. The overall Objective of this project is to develop techniques that will allow us to measure the effects of ethanol administration on the rates of synthesis of the neurotransmitters, glutamate, GABA and aspartate, from glucose in the intact, conscious rat. The rates of neurotransmitter synthesis and patterns of glucose metabolism will be determined using "C NMR spectroscopy to analyze for the distribution of isotope into glucose metabolites. This technique allows for a quantitative evaluation of glucose incorporation into metabolites, including the neurotransmitters, by identifying the distribution of "C into particular carbon atoms within a metabolite. A long range goal is to determine the impact of ethanol on the metabolism of glucose through the glycolytic, anaplerotic and oxidative pathways in order to relate alterations in glucose metabolism to changes in the rates of neurotransmitter synthesis. Studies will be carried out utilizing a dose of ethanol which stimulates motor activity (0.25 g/kg body weight) and one which has a -sedative effect on the organism (1.0 g/kg body weight). It is expected that these two doses will influence the patterns of glucose metabolism and neurotransmitter synthesis differently since it has been previously demonstrated that they exert opposite effects on the uptake of glucose in certain brain regions. Techniques will also be developed to study the effects of ethanol on glucose and neurotransmitter metabolism in mixtures of isolated astrocytes and neurons (co-cultures). Once this latter technology is established, it will be utilized in future studies to differentiate between direct and indirect effects of ethanol on glucose and neurotransmitter metabolism in the brain, particularly in the cerebral cortex. 1:3C NMR spectroscopy will also be utilized in development of the techniques for following glucose and neurotransmitter metabolism in the co-cultures.