Document Detail


Localization of the Na(+)-coupled neutral amino acid transporter 2 in the cerebral cortex.
MedLine Citation:
PMID:  16616430     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
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.
Authors:
M Melone; H Varoqui; J D Erickson; F Conti
Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't     Date:  2006-04-17
Journal Detail:
Title:  Neuroscience     Volume:  140     ISSN:  0306-4522     ISO Abbreviation:  Neuroscience     Publication Date:  2006 Jun 
Date Detail:
Created Date:  2006-05-15     Completed Date:  2006-08-10     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7605074     Medline TA:  Neuroscience     Country:  United States    
Other Details:
Languages:  eng     Pagination:  281-92     Citation Subset:  IM    
Affiliation:
Department of Neuroscience (Section of Physiology), Università Politecnica delle Marche, Via Tronto 10/A, Torrette di Ancona, I-60020 Ancona, Italy.
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MeSH Terms
Descriptor/Qualifier:
Amino Acid Transport System A / 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:
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

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