5-Hydroxytryptamine Stimulates [3H]Dopamine Release from the Fish Retina |
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Authors: | S Kato T Teranishi C H Kuo K Negishi |
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Institution: | Department of Neurophysiology, Neuroinformation Research Institute, University of Kanazawa School of Medicine;Department of Pharmacology, Cancer Research Institute, University of Kanazawa, Kanazawa, Ishikawa, Japan |
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Abstract: | Abstract: Serotonin (5-hydroxytryptamine, 5-HT; 0.5 μM 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-hydroxytrypto-phan, 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 m M ) produced a large increase in 3H]DA release from the particulate fractions, but this action was Ca2+-independent. Further, no significant release of 3H]γ-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. |
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Keywords: | Fish retina Dopamine cells Indoleamine-accumulating cells 5-Hydroxytryptamine [3H]Dopa-mine release |
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