5-hydroxytryptamine stimulates [3H]dopamine release from the fish retina.
Serotonin (5-hydroxytryptamine, 5-HT; 0.5 micro M and above) stimulated the release of [3H]dopamine ([3H]DA) from particulate fractions of the carp (Cyprinus carpio) retina. The 5-HT effect was dose- and Ca2+-dependent, and was structurally specific. A similar response was not elicited by the other indoles (5,6-dihydroxytryptamine, 5,7-dihydroxytryptamine, 5-hydroxytryptophan, or 5-hydroxyindoleacetic acid) examined. An increase in [3H]DA release was elicited by addition of 5-HT agonists (5-methoxytryptamine, 5-methoxy-N,N-dimethyltryptamine, and tryptamine), but not antagonized by three 5-HT antagonists (metergolin, methysergide, and spiperone). Either DA alone or noradrenaline (0.5 mM) produced a large increase in [3H]DA release from the particulate fractions, but this action was Ca2+-independent. Further, no significant release of [3H] gamma-aminobutyric acid could be evoked by 5-HT (0.5 mM) under similar experimental conditions. Taken together, the present data suggest that 5-HT stimulates [3H]DA release from the fish retina through a specific receptor-mediated mechanism on dopaminergic terminals, but not through an exchange or nonspecific phenomenon.
D008735:5-Methoxytryptamine / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002347:Carps / Q000378:metabolism*; D003530:Cyprinidae / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006651:Histocytochemistry; D008732:Methoxydimethyltryptamines / Q000494:pharmacology; D012160:Retina / Q000187:drug effects / Q000378:metabolism*; D012701:Serotonin / Q000494:pharmacology*; D014363:Tryptamines / Q000494:pharmacology
D008732:Methoxydimethyltryptamines; D014363:Tryptamines; D012701:Serotonin; D008735:5-Methoxytryptamine; C030820:tryptamine; D002118:Calcium; D004298:Dopamine