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AMPA-preferring receptors mediate excitatory synaptic inputs to retinal ganglion cells.
- Source :
-
Journal of neurophysiology [J Neurophysiol] 1997 Jan; Vol. 77 (1), pp. 57-64. - Publication Year :
- 1997
-
Abstract
- Pharmacological studies were performed to determine whether alpha-amino-3-hydroxy-5-methyl-4-isoazoleprionic acid (AMPA)- and/or kainate (KA)-preferring receptors mediate excitatory synaptic inputs to tiger salamander retinal ganglion cells. Excitatory postsynaptic currents (EPSCs), evoked either by light or by stimulating bipolar cells with puffs of K+, were measured using whole cell recording techniques in the tiger salamander retinal slice. The AMPA/KA component of the EPSCs was isolated by including antagonists of glycine-, gamma-aminobutyric acid (GABA)- and NMDA-receptors in the bath. The AMPA-preferring receptor antagonists, 1-(4-aminophenyl)-4-methyl-7,8-methylenedioxy-5H-2,3-benzodiazepine hydrochloride (GYKI-52466) and 1-(4-aminophenyl)-3-methylcarbamyl-4-methyl-7,8-methylenedioxy-3,4 - dihydro-5H-2,3-benzodiazepine (GYKI-53665), reduced light-evoked EPSCs and K+ puff-evoked EPSCs amplitudes in a concentration-dependent manner. The IC50 values for GYKI-52466 were 3.6 and 4.2 microM for the light- and puff-evoked responses, respectively. The more potent GYKI-53665 had IC50 values of 0.7 microM for both the light- and puff evoked responses. KA activates both KA- and AMPA-preferring receptors. KA-evoked currents were completely blocked by 10-40 microM GYKI-53665, indicating that little or no excitatory synaptic current was mediated by KA-preferring receptors. Concanavalin A, a compound that preferentially potentiates responses mediated by KA-preferring receptors, did not enhance either EPSCs or glutamate-evoked responses. By contrast, cyclothiazide, which selectively enhances AMPA-preferring receptor mediated responses, was found to enhance both EPSCs and glutamate-evoked currents. Our results indicate that the non-NMDA component of ganglion cell EPSCs is mediated by AMPA-preferring receptors and not significantly by KA-preferring receptors.
- Subjects :
- Ambystoma
Animals
Benzodiazepines pharmacology
Dendrites drug effects
Electrophysiology
Evoked Potentials, Visual drug effects
Evoked Potentials, Visual physiology
Excitatory Amino Acid Agonists pharmacology
Excitatory Amino Acid Antagonists pharmacology
Membrane Potentials drug effects
Membrane Potentials physiology
Microelectrodes
Patch-Clamp Techniques
Photic Stimulation
Potassium pharmacology
Receptors, AMPA antagonists & inhibitors
Receptors, AMPA drug effects
Receptors, Neurotransmitter drug effects
Retinal Ganglion Cells drug effects
Stimulation, Chemical
Anti-Anxiety Agents
Receptors, AMPA physiology
Receptors, Neurotransmitter physiology
Retinal Ganglion Cells physiology
Subjects
Details
- Language :
- English
- ISSN :
- 0022-3077
- Volume :
- 77
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- Journal of neurophysiology
- Publication Type :
- Academic Journal
- Accession number :
- 9120596
- Full Text :
- https://doi.org/10.1152/jn.1997.77.1.57