title: Circadian melatonin rhythms in cultured zebrafish pineals are not affected by catecholamine receptor agonists.
abstract: Catecholamine receptors of multiple classes have been shown to influence pineal melatonin synthesis in a species-specific manner. In these experiments, the effects of catecholamine receptor agonists on circadian melatonin rhythms of zebrafish (Danio rerio) pineal in vitro were examined. Cyclic application of adrenergic receptor agonists (norepinephrine, phenylephrine, clonidine, and isoproterenol) had no effect on zebrafish pineal melatonin release, nor on the circadian oscillator that regulates melatonin rhythms. Pineal melatonin release was partially suppressed by quinpirole, a D2 dopamine receptor agonist, but cyclic application of quinpirole did not reset the pineal circadian oscillator. Pineal melatonin release was unaffected by either dopamine or SKF38393, a D1 receptor agonist, suggesting that the effects of quinpirole were not mediated by dopamine receptors. The regulatory mechanisms underlying pineal melatonin rhythms appear to differ among teleosts.
authors.affiliation: Department of Biology, University of Houston, 4800 Calhoun, Houston, Texas, 77204-5513, USA.
authors.forename: G M
authors.initials: GM
authors.lastname: Cahill
mesh_terms: D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine / Q000494:pharmacology; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D002940:Circadian Rhythm / Q000187:drug effects*; D003000:Clonidine / Q000494:pharmacology; D004298:Dopamine / Q000494:pharmacology; D018491:Dopamine Agonists / Q000494:pharmacology*; D007545:Isoproterenol / Q000494:pharmacology; D008550:Melatonin / Q000032:analysis / Q000276:immunology / Q000378:metabolism*; D009638:Norepinephrine / Q000494:pharmacology; D009924:Organ Culture Techniques; D010656:Phenylephrine / Q000494:pharmacology; D017440:Photoperiod; D010870:Pineal Gland / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D019257:Quinpirole / Q000494:pharmacology; D011863:Radioimmunoassay; D013997:Time Factors; D015027:Zebrafish
chemical_list: D000316:Adrenergic alpha-Agonists; D000318:Adrenergic beta-Agonists; D018491:Dopamine Agonists; D010656:Phenylephrine; D019257:Quinpirole; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; D008550:Melatonin; D007545:Isoproterenol; D003000:Clonidine; D004298:Dopamine; D009638:Norepinephrine