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A(2a) Adenosine Receptor Mediates PKA-Dependent Glutamate Release from Synaptic-like Vesicles and Ca Efflux from an IP(3)- and Ryanodine-Insensitive Intracellular Calcium Store in Astrocytes.
MedLine Citation:
PMID:  23154210     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Background/Aims: The mechanism underlying transmitter release from astrocytes is not fully understood. The present study examined A(2a) adenosine receptor-mediated glutamate release and intracellular Ca(2+) rise in cultured rat hippocampal astrocytes. Methods: Intracellular amino acids were measured with HPLC. Glutamate release from astrocytes and intracellular Ca(2+) mobilizations were monitored in the NADH imaging, FM1-43 imaging, and fura-2 imaging. The siRNA to silence the A(2a) adenosine receptor-targeted gene was constructed and transfected into cells. Results: Glutamate was condensed in 'synaptic-like vesicle' fractions. In the NADH imaging, CGS21680, an agonist of A2a adenosine receptors, increased NADH fluorescent signals, that reflects glutamate release, and the effect was inhibited by DMPX, an inhibitor of A(2a) adenosine receptors, H-89, a PKA inhibitor, vesicular transport inhibitors, or botulinum toxin-A, an exocytosis inhibitor. In the FM1-43 imaging to see vesicular recycling, CGS21680 decreased FM1-43 fluorescent signals, that was also prevented by DMPX, H-89, vesicular transport inhibitors, or botulinum toxin-A. CGS21680 increased intracellular Ca(2+) concentrations both in Ca(2+)-containing and -free extracellular solution. The Ca(2+) rise was inhibited by DMPX, H-89, or the vesicular transport inhibitor brefeldin A, but it was not affected by inhibitors for phospholipase C, IP(3) receptor, and ryanodine receptor. CGS21680-induced glutamate release and intracellular Ca(2+) rise were prevented by knocking-down A(2a) adenosine receptor. Conclusion: The results of the present study show that A(2a) adenosine receptor/PKA promotes glutamate release from synaptic-like vesicles and stimulates Ca(2+) efflux from an IP(3)- and ryanodine-insensitive intracellular calcium store.
Authors:
Takeshi Kanno; Tomoyuki Nishizaki
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-11-16
Journal Detail:
Title:  Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology     Volume:  30     ISSN:  1421-9778     ISO Abbreviation:  Cell. Physiol. Biochem.     Publication Date:  2012 Nov 
Date Detail:
Created Date:  2012-11-16     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9113221     Medline TA:  Cell Physiol Biochem     Country:  -    
Other Details:
Languages:  ENG     Pagination:  1398-1412     Citation Subset:  -    
Affiliation:
Division of Bioinformation, Department of Physiology, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Japan.
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