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Cholinergic modulation of dopamine release and horizontal cell coupling in mudpuppy retina

By Karen L. Myhr and John S. McReynolds

Abstract

AbstractThe effects of cholinergic agonists and antagonists on electrical coupling between horizontal cells were studied in dark-adapted mudpuppy retinas. Carbachol and the nicotinic agonist 1,1-dimethyl-4-phenylpiperazinium (DMPP) uncoupled horizontal cells, but the muscarinic agonist oxotremorine did not. The uncoupling effects of carbachol and DMPP were blocked by the nicotinic antagonistd-tubocurarine and by the dopamine antagonist fluphenazine, indicating that carbachol uncoupled horizontal cells by stimulating dopamine release via nicotinic receptors. Carbachol also caused an increase in release of [3H]dopamine from retinas.d-Tubocurarine increased horizontal cell coupling, indicating that tonic cholinergic input was present in dark-adapted retinas.d-Tubocurarine did not reduce light-evoked uncoupling of horizontal cells, suggesting that cholinergic neurons are not an essential part of the direct pathway by which light causes an immediate increase in dopamine release

Publisher: Published by Elsevier Ltd.
Year: 1996
DOI identifier: 10.1016/S0042-6989(96)00131-9
OAI identifier:

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