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Metabolic fate of a high concentration of glutamine and glutamate in rat brain slices: a ¹³C NMR study.

Authors :
El Hage M
Conjard-Duplany A
Baverel G
Martin G
Source :
Neurochemistry international [Neurochem Int] 2011 Jul; Vol. 58 (8), pp. 896-903. Date of Electronic Publication: 2011 Feb 19.
Publication Year :
2011

Abstract

This study was performed to analyze the metabolic fate of a high concentration (5 mM) of glutamine and glutamate in rat brain slices and the participation of these amino acids in the glutamine-glutamate cycle. For this, brain slices were incubated for 60 min with [3-¹³C]glutamine or [3-¹³C]glutamate. Tissue plus medium extracts were analyzed by enzymatic and ¹³C NMR measurements and fluxes through pathways of glutamine and glutamate metabolism were calculated. We demonstrate that both substrates were utilized and oxidized at high rates by rat brain slices and served as precursors of neurotransmitters, tricarboxylic acid (TCA) cycle intermediates and alanine. In order to determine the participation of glutamine synthetase in the appearance of new glutamine molecules with glutamine as substrate, brain slices were incubated with [3-¹³C]glutamine in the presence of methionine sulfoximine, a specific inhibitor of glutamine synthetase. Our results indicate that 36.5% of the new glutamine appeared was glutamine synthetase-dependent and 63.5% was formed from endogenous substrates. Flux through glutamic acid decarboxylase was higher with glutamine than with glutamate as substrate whereas fluxes from α-ketoglutarate to glutamate and through glutamine synthetase, malic enzyme, pyruvate dehydrogenase, pyruvate carboxylase and citrate synthase were in the same range with both substrates.<br /> (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Details

Language :
English
ISSN :
1872-9754
Volume :
58
Issue :
8
Database :
MEDLINE
Journal :
Neurochemistry international
Publication Type :
Academic Journal
Accession number :
21338644
Full Text :
https://doi.org/10.1016/j.neuint.2011.02.018