| Compartmentation of brain glutamate metabolism in neurons and glia. | |
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MedLine Citation:
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PMID: 10736375 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Intrasynaptic [glutamate] must be kept low in order to maximize the signal-to-noise ratio after the release of transmitter glutamate. This is accomplished by rapid uptake of glutamate into astrocytes, which convert glutamate into glutamine. The latter then is released to neurons, which, via mitochondrial glutaminase, form the glutamate that is used for neurotransmission. This pattern of metabolic compartmentation is the "glutamate-glutamine cycle." This model is subject to the following two important qualifications: 1) brain avidly oxidizes glutamate via aspartate aminotransferase; and 2) because almost no glutamate crosses from blood to brain, it must be synthesized in the central nervous system (CNS). The primary source of glutamate carbon is glucose, and a major source of glutamate nitrogen is the branched-chain amino acids, which are transported rapidly into the CNS. This arrangement accomplishes the following: 1) maintenance of low external [glutamate], thereby maximizing signal-to-noise ratio upon depolarization; 2) the replenishing of the neuronal glutamate pool; 3) the "trafficking" of glutamate through the extracellular fluid in a nonneuroactive form (glutamine); 4) the importation of amino groups from blood, thus maintaining brain nitrogen homeostasis; and 5) the oxidation of glutamate/glutamine, a process that confers an additional level of control in terms of the regulation of brain glutamate, aspartate and gamma-aminobutyric acid. |
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Authors:
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Y Daikhin; M Yudkoff |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.; Review |
Journal Detail:
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Title: The Journal of nutrition Volume: 130 ISSN: 0022-3166 ISO Abbreviation: J. Nutr. Publication Date: 2000 Apr |
Date Detail:
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Created Date: 2000-04-25 Completed Date: 2000-04-25 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 0404243 Medline TA: J Nutr Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 1026S-31S Citation Subset: IM |
Affiliation:
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Department of Pediatrics, University of Pennsylvania School of Medicine, Children's Hospital of Philadelphia, PA 19104-4318, USA. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Brain / cytology, metabolism* Glutamic Acid / metabolism* Glutamine / metabolism Neuroglia / metabolism* Neurons / metabolism* Synaptic Transmission / physiology |
| Grant Support | |
ID/Acronym/Agency:
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HD26979/HD/NICHD NIH HHS; NS34900/NS/NINDS NIH HHS; NS37915/NS/NINDS NIH HHS |
| Chemical | |
Reg. No./Substance:
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56-85-9/Glutamine; 56-86-0/Glutamic Acid |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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