title: Serotonin-induced brain glycogenolysis in rainbow trout (Oncorhynchus mykiss).
abstract: In this study, we evaluated the serotonin-mediated control of cerebral glycogen levels in the rainbow trout, Oncorhynchus mykiss. Intracerebroventricular (i.c.v.) administration of serotonin (5-HT) to normoglycemic trout (time and dose response) decreased glycogen levels in the brain and increased brain glycogen phosphorylase activity (time response). In hypoglycemic fish (that had been fasted for 5 and 10 days), there was a time-dependent decrease in brain glycogen levels; under these conditions, i.c.v. administration of 5-HT also reduced the brain glycogen content in fish that had been fasted for 5 days. In fish with local cerebral hypoglycemia (induced by 2-DG administration), the glycogen levels decreased and, as above, i.c.v. administration of 5-HT also lowered the glycogen content. In hyperglycemic fish, 5-HT did not affect glycogen levels. Administration of receptor agonists 5-HT1A (8-OH-DPAT), 5-HT1B (anpirtoline and CP93129) or 5-HT2 (α-m-5-HT) decreased the brain glycogen levels. This effect was antagonized by the administration of receptor antagonists 5-HT1A (WAY100135 and NAN190), 5-HT1B (NAS181) and 5-HT2B/C (SB206553). Administration of the receptor agonists (±)-DOI (5-HT2A/2C), m-CPP (5-HT2B/2C), BW723C86 (5-HT2B) and WAY 161503 (5-HT2C) led to decreases in the levels of brain glycogen. We found that 5-HT is involved in the modulation of brain glycogen homeostasis in the rainbow trout, causing a glycogenolytic effect when fish are in a normoglycemic or hypoglycemic state, but not when they are in a hyperglycemic state. 5-HT1A, 5-HT1B, 5HT2B and 5-HT2C-like receptors appeared to be involved in the glycogenolytic action of 5-HT, although the effect mediated by 5-HT1A or 5-HT1B was apparently stronger.
authors.affiliation: Laboratorio de Fisiología Animal (Instituto de Acuicultura), Facultad de Biología, Universidad de Santiago de Compostela, 15782 Santiago de Compostela,  Spain.
authors.forename: Jorge J
authors.initials: JJ
authors.lastname: Pérez-Maceira
authors.forename: María J
authors.initials: MJ
authors.lastname: Mancebo
authors.forename: Manuel
authors.initials: M
authors.lastname: Aldegunde
mesh_terms: D000818:Animals; D001578:Benzopyrans / Q000008:administration & dosage / Q000494:pharmacology; D001921:Brain / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism*; D006003:Glycogen / Q000378:metabolism; D025002:Glycogen Phosphorylase, Brain Form / Q000378:metabolism; D050261:Glycogenolysis / Q000187:drug effects*; D007211:Indoles / Q000008:administration & dosage / Q000494:pharmacology; D007274:Injections, Intraperitoneal; D007276:Injections, Intraventricular; D009025:Morpholines / Q000008:administration & dosage / Q000494:pharmacology; D017686:Oncorhynchus mykiss / Q000378:metabolism*; D010879:Piperazines / Q000008:administration & dosage / Q000494:pharmacology; D011719:Pyrazines / Q000008:administration & dosage / Q000494:pharmacology; D011725:Pyridines / Q000008:administration & dosage / Q000494:pharmacology; D011810:Quinoxalines / Q000008:administration & dosage / Q000494:pharmacology; D044263:Receptors, Serotonin, 5-HT1 / Q000378:metabolism; D012701:Serotonin / Q000008:administration & dosage / Q000494:pharmacology*; D058825:Serotonin 5-HT1 Receptor Agonists / Q000008:administration & dosage / Q000494:pharmacology; D058829:Serotonin 5-HT1 Receptor Antagonists / Q000008:administration & dosage / Q000494:pharmacology; D013876:Thiophenes / Q000008:administration & dosage / Q000494:pharmacology; D013997:Time Factors
chemical_list: C092430:1-(5-(2-thenyloxy)-1H-indol-3-yl)propan-2-amine; C112429:2-(((3-(morpholinylmethyl)-2H-chromen-8-yl)oxy)methyl)morpholine; C502777:8,9-dichloro-2,3,4,4a-tetrahydro-1H-pyrazino(1,2-a)quinoxalin-5(6H)-one; D001578:Benzopyrans; D007211:Indoles; D009025:Morpholines; D010879:Piperazines; D011719:Pyrazines; D011725:Pyridines; D011810:Quinoxalines; D044263:Receptors, Serotonin, 5-HT1; D058825:Serotonin 5-HT1 Receptor Agonists; D058829:Serotonin 5-HT1 Receptor Antagonists; D013876:Thiophenes; C058895:1-(2-methoxyphenyl)-4-(4-(2-phthalimido)butyl)piperazine; C081293:WAY 100135; D012701:Serotonin; D006003:Glycogen; C094868:SB 206553; D025002:Glycogen Phosphorylase, Brain Form