| Localization of the Na(+)-coupled neutral amino acid transporter 2 in the cerebral cortex. | |
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MedLine Citation:
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PMID: 16616430 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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We studied the distribution and cellular localization of Na(+)-coupled neutral amino acid transporter 2, a member of the system A family of amino acid transporters, in the rat and human cerebral cortex using immunocytochemical methods. Na(+)-coupled neutral amino acid transporter 2-positive neurons were pyramidal and non-pyramidal, and Na(+)-coupled neutral amino acid transporter 2/GABA double-labeling studies revealed that Na(+)-coupled neutral amino acid transporter 2 was highly expressed by GABAergic neurons. Double-labeling studies with the synaptophysin indicated that rare axon terminals express Na(+)-coupled neutral amino acid transporter 2. Na(+)-coupled neutral amino acid transporter 2-immunoreactivity was also found in astrocytes, leptomeninges, ependymal cells and choroid plexus. Electron microscopy showed robust Na(+)-coupled neutral amino acid transporter 2-immunoreactivity in the somato-dendritic compartment of neurons and in glial processes, but, as in the case of double-labeling studies, failed to reveal Na(+)-coupled neutral amino acid transporter 2-immunoreactivity in terminals. To rule out the possibility that the absence of Na(+)-coupled neutral amino acid transporter 1- and Na(+)-coupled neutral amino acid transporter 2-positive terminals was due to insufficient antigen detection, we evaluated Na(+)-coupled neutral amino acid transporter 1/synaptophysin and Na(+)-coupled neutral amino acid transporter 2/synaptophysin coexpression using non-standard immunocytochemical procedures and found that Na(+)-coupled neutral amino acid transporter 1 and Na(+)-coupled neutral amino acid transporter 2+ terminals were rare in all conditions. These findings indicate that Na(+)-coupled neutral amino acid transporter 1 and Na(+)-coupled neutral amino acid transporter 2 are virtually absent in cortical terminals, and suggest that they do not contribute significantly to replenishing the Glu and GABA transmitter pools through the glutamate-glutamine cycle. The strong expression of Na(+)-coupled neutral amino acid transporter 2 in the somato-dendritic compartment and in non-neuronal elements that are integral parts of the blood-brain and brain-cerebrospinal fluid barrier suggests that Na(+)-coupled neutral amino acid transporter 2 plays a role in regulating the levels of Gln and other amino acids in the metabolic compartment of cortical neurons. |
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Authors:
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M Melone; H Varoqui; J D Erickson; F Conti |
Publication Detail:
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Type: Comparative Study; Journal Article; Research Support, Non-U.S. Gov't Date: 2006-04-17 |
Journal Detail:
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Title: Neuroscience Volume: 140 ISSN: 0306-4522 ISO Abbreviation: Neuroscience Publication Date: 2006 Jun |
Date Detail:
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Created Date: 2006-05-15 Completed Date: 2006-08-10 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 7605074 Medline TA: Neuroscience Country: United States |
Other Details:
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Languages: eng Pagination: 281-92 Citation Subset: IM |
Affiliation:
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Department of Neuroscience (Section of Physiology), Università Politecnica delle Marche, Via Tronto 10/A, Torrette di Ancona, I-60020 Ancona, Italy. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Amino Acid Transport System A
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metabolism* Animals Blotting, Western / methods Calcium-Binding Proteins / metabolism Cerebral Cortex / cytology*, metabolism Female Glial Fibrillary Acidic Protein / metabolism Humans Immunohistochemistry / methods Male Membrane Proteins / metabolism Microscopy, Electron, Transmission / methods Middle Aged Muscle Proteins / metabolism Neurons / metabolism*, ultrastructure Phosphopyruvate Hydratase / metabolism Rats Rats, Sprague-Dawley gamma-Aminobutyric Acid / metabolism |
| Chemical | |
Reg. No./Substance:
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0/Amino Acid Transport System A; 0/Calcium-Binding Proteins; 0/Glial Fibrillary Acidic Protein; 0/Membrane Proteins; 0/Muscle Proteins; 0/SLC38A2 protein, human; 0/syntrophin alpha1; 56-12-2/gamma-Aminobutyric Acid; EC 4.2.1.11/Phosphopyruvate Hydratase |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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