Cholinergic modulation of dopamine release and horizontal cell coupling in mudpuppy retina.
The 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 antagonist D-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.
Myhr
K L
KL
Department of Physiology, University of Michigan, Ann Arbor 48109-0622, USA.
McReynolds
J S
JS
D000109:Acetylcholine / Q000502:physiology; D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D002450:Cell Communication / Q000187:drug effects; D018679:Cholinergic Agonists / Q000494:pharmacology*; D018680:Cholinergic Antagonists / Q000494:pharmacology*; D046508:Culture Techniques; D004298:Dopamine / Q000378:metabolism*; D005476:Fluphenazine / Q000494:pharmacology; D009338:Necturus maculosus / Q000502:physiology*; D010775:Photic Stimulation; D011978:Receptors, Nicotinic / Q000502:physiology; D012160:Retina / Q000166:cytology / Q000187:drug effects* / Q000502:physiology
D018679:Cholinergic Agonists; D018680:Cholinergic Antagonists; D011978:Receptors, Nicotinic; D002217:Carbachol; D000109:Acetylcholine; D005476:Fluphenazine; D004298:Dopamine