THE INFLUENCE OF INTRAVENTRICULARLY INJECTED AMINO ACID EXCITANTS ON THE LABELLING OF ENDOGENOUS BRAIN AMINO ACIDS FROM [U-14C]ACETATE IN NEMBUTALIZED MICE |
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Authors: | J. C. Watkins |
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Affiliation: | MRC Neuropsychiatry Unit, Medical Research Council Laboratories, Carshalton, Surrey, England |
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Abstract: | Mice were anaesthetized with nembutal and the effects of intraventricularly injected excitant amino acids on [U-14C]acetate metabolism were investigated. The natural excitant amino acids, l -glutamate and l -aspartate, reduced the incorporation of 14C from [U-14C]acetate into glutamine, GAB A and possibly alanine. The synthetic excitant amino acid, N-methyl-d -aspartate caused a reduction in the incorporation of 14C from intraventricularly injected [U-14C]acetate into all of the brain amino acids labelled by [U-14C]acetate within 5 min. It is suggested that these effects may be due to changes in pool sizes of tricarboxylic cycle intermediates, to inhibition of acetyl-CoA formation, or both. Differences in the metabolic effects of the synthetic and natural excitants are interpreted in terms of the uptake of the natural amino acids into glutamine-forming pool(s) of glutamate metabolism. |
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