Functional role of GABA in cat retina: I. Effects of GABAA agonists

Putative GABAergic mechanisms were studied in perfused cat retina by means of intracellular recording and application of GABA and the GABAA agonists delta-amino valeric acid (dAVA), muscimol, and THIP. In contrast to results reported previously for cold-blooded vertebrates, introduction of 20 mM GAB...

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Bibliographic Details
Published inVisual neuroscience Vol. 12; no. 4; p. 641
Main Authors Frumkes, T E, Nelson, R
Format Journal Article
LanguageEnglish
Published England 01.07.1995
Subjects
Animals
Cats
GABA Agonists - pharmacology
gamma-Aminobutyric Acid - pharmacology
gamma-Aminobutyric Acid - physiology
Membrane Potentials - physiology
Neurons - physiology
Perfusion
Photic Stimulation
Photoreceptor Cells - physiology
Receptors, GABA-A - metabolism
Retina - cytology
Retina - drug effects
Retina - physiology
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Summary:Putative GABAergic mechanisms were studied in perfused cat retina by means of intracellular recording and application of GABA and the GABAA agonists delta-amino valeric acid (dAVA), muscimol, and THIP. In contrast to results reported previously for cold-blooded vertebrates, introduction of 20 mM GABA into the superfusate had no influence upon the response properties of cat retinal horizontal cells (HCs). In common with results reported in cold-blooded vertebrates, introduction of the GABAA agonists dAVA (2-12 mM) and THIP or muscimol (0.2-1 mM) had four consistent reversible influences upon the response properties of cat retinal HCs: (1) they reduced photic-response amplitude, (2) slowed response onset, (3) slowed response offset, and (4) depolarized the dark membrane potential. Both rod and cone signal components were affected. GABAA agonists had similar influences upon both the time course and amplitude of responses recorded from amacrine and ganglion cells. In all cell types examined, the influence upon response kinetics was made particularly apparent with rapidly flickering stimuli. Flicker responses were reduced in amplitude much more than sustained responses. These results suggest that, in addition to other influences, GABAergic action serves to modify the time course of photic responses in both the inner and outer plexiform layer of mammalian retina making responses slower and less phasic.
ISSN:0952-5238
DOI:10.1017/S0952523800008932