Document Detail

Intracellular calcium release resulting from mGluR1 receptor activation modulates GABAA currents in wide-field retinal amacrine cells: a study with caffeine.
MedLine Citation:
PMID:  12814357     Owner:  NLM     Status:  MEDLINE    
The modulatory action of calcium (Ca2+) released from intracellular stores on GABAA receptor-mediated current was investigated in wide-field amacrine cells isolated from the teleost, Morone chrysops, retina. Caffeine, ryanodine or inositol 1,4,5-triphosphate (IP3) markedly inhibited the GABAA current by elevating [Ca2+]i. The inhibition resulted from the activation of a Ca2+--> Ca2+/calmodulin --> calcineurin cascade. Long (>12 s) exposure to glutamate mimicked the caffeine effect, i.e. it inhibited the GABAA current by elevating [Ca2+]i through mGluR1 receptor activation and consequent IP3 generation. This pathway provides a 'timed' disinhibitory mechanism to potentiate excitatory postsynaptic potentials in wide-field amacrine cells. It occurs as a result of the suppression of GABA-mediated conductances as a function of the duration of presynaptic excitatory input activity. This is much like some forms of long-term potentiation in the central nervous system. In a local retinal circuit this will selectively accentuate particular excitatory inputs to the wide-field amacrine cell. Similar to other neural systems, we suggest that activity-dependent postsynaptic disinhibition is an important feature of the signal processing in the inner retina.
Jozsef Vigh; Eric M Lasater
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The European journal of neuroscience     Volume:  17     ISSN:  0953-816X     ISO Abbreviation:  Eur. J. Neurosci.     Publication Date:  2003 Jun 
Date Detail:
Created Date:  2003-06-19     Completed Date:  2003-09-04     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  8918110     Medline TA:  Eur J Neurosci     Country:  France    
Other Details:
Languages:  eng     Pagination:  2237-48     Citation Subset:  IM    
Dept. of Ophthalmology and Visual Sciences, John Moran Eye Center, University of Utah, Health Sciences Center, Salt Lake City, UT 84132, USA.
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MeSH Terms
Amacrine Cells / drug effects*,  physiology
Anticoagulants / pharmacology
Bicuculline / pharmacology
Caffeine / pharmacology*
Calcium / metabolism*
Calcium Channels / metabolism
Cells, Cultured
Central Nervous System Stimulants / pharmacology*
Chelating Agents / pharmacology
Dose-Response Relationship, Drug
Drug Interactions
Egtazic Acid / analogs & derivatives*,  pharmacology
Electric Conductivity / diagnostic use
Enzyme Inhibitors / pharmacology
Excitatory Amino Acid Agonists / pharmacology
Extracellular Space / metabolism
GABA Antagonists / pharmacology
Glutamic Acid / physiology
Heparin / pharmacology
Inositol 1,4,5-Trisphosphate / pharmacology
Inositol 1,4,5-Trisphosphate Receptors
Kainic Acid / pharmacology
Membrane Potentials / drug effects
Methoxyhydroxyphenylglycol / analogs & derivatives*,  pharmacology
Organophosphorus Compounds / pharmacology
Patch-Clamp Techniques / methods
Receptors, Cytoplasmic and Nuclear / metabolism
Receptors, GABA-A / physiology*
Receptors, Metabotropic Glutamate / antagonists & inhibitors,  metabolism*
Retina / cytology*
Ryanodine / pharmacology
alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / pharmacology
gamma-Aminobutyric Acid / pharmacology
Grant Support
Reg. No./Substance:
0/Anticoagulants; 0/Calcium Channels; 0/Central Nervous System Stimulants; 0/Chelating Agents; 0/Enzyme Inhibitors; 0/Excitatory Amino Acid Agonists; 0/GABA Antagonists; 0/Inositol 1,4,5-Trisphosphate Receptors; 0/Organophosphorus Compounds; 0/Receptors, Cytoplasmic and Nuclear; 0/Receptors, GABA-A; 0/Receptors, Metabotropic Glutamate; 0/metabotropic glutamate receptor type 1; 127729-35-5/3-aminopropyl(methyl)phosphinic acid; 15662-33-6/Ryanodine; 3343-19-9/dihydroxyphenylethylene glycol; 485-49-4/Bicuculline; 487-79-6/Kainic Acid; 534-82-7/Methoxyhydroxyphenylglycol; 56-12-2/gamma-Aminobutyric Acid; 56-86-0/Glutamic Acid; 58-08-2/Caffeine; 67-42-5/Egtazic Acid; 7440-70-2/Calcium; 77521-29-0/alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; 85166-31-0/Inositol 1,4,5-Trisphosphate; 85233-19-8/1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; 9005-49-6/Heparin

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