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Dopaminergic Mechanisms in the Teleost Retina
Author(s) -
Watling Keith J.,
Dowling John E.
Publication year - 1981
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1981.tb01628.x
Subject(s) - apomorphine , cyclase , dopamine , endocrinology , medicine , chemistry , spiperone , adenylate kinase , dopaminergic , stimulation , dopamine antagonist , dopamine receptor , agonist , pharmacology , biology , haloperidol , biochemistry , receptor
A specific dopamine‐sensitive adenylate cyclase has been identified in homogenates of the teleost (carp) retina. Maximal stimulation by 100 μM‐dopamine resulted in a 5‐10‐fold increase in adenylate cyclase activity with half‐maximal stimulation occurring at a concentration of 1 μM. l ‐Noradrenaline and l ‐adrenaline were some 10 times less potent than dopamine whilst the α‐and β‐adrenoreceptor agonists, l ‐phenylephrine and dl ‐isoprenaline were inactive. Apomorphine elicited a partial stimulation of adenylate cyclase activity whilst various ergot alkaloids produced mixed agonist/antagonist responses. Dopamine‐stimulated adenylate cyclase activity was potently antagonised by various neuroleptic drugs including fluphenazine, α‐flupenthixol and α‐piflutixol, and to a lesser extent by the butyrophenone derivatives haloperidol and spiperone. The benzamide derivatives, metoclopramide and sulpiride. together with the α‐ and β‐adrenoreceptor blocking agents, phentolamine and propranolol respectively, were essentially inactive at blocking dopamine‐stimulated adenylate cyclase activity. These data suggest the presence of a highly specific dopamine‐sensitive adenylate cyclase in homogenates of teleost retina possessing similar pharmacological properties to the dopamine‐sensitive adenylate cyclase observed in the mammalian central nervous system.