title: Catabolism of intracerebroventricularly injected 5-hydroxytryptamine in mouse: effect of coinjection of tryptamine and several pretreatments.
abstract: The catabolism of intracerebroventricularly injected 5-hydroxytryptamine in mouse brain was investigated. Pretreatment of animals with the 5-hydroxytryptamine type 1 receptor antagonist metergoline, the 5-hydroxytryptamine type 2 receptor antagonist ketanserin, the 5-hydroxytryptamine reuptake inhibitor fluoxetine, or the selective 5-hydroxytryptamine neurotoxin 5,7-dihydroxytryptamine failed to alter the rate of catabolism of intracerebroventricularly administered 5-hydroxytryptamine. The monoamine oxidase inhibitor tranylcypromine effectively blocked degradation of injected 5-hydroxytryptamine and accumulation of 5-hydroxyindoleacetic acid. Coinjection of tryptamine with 5-hydroxytryptamine reduced the rate of conversion of 5-hydroxytryptamine to 5-hydroxyindoleacetic acid. These results indicate that intracerebroventricularly administered 5-hydroxytryptamine is removed by a monoamine oxidase dependent system. This catabolism is not affected by inhibition of presynaptic uptake, 5-hydroxytryptamine receptor type 1 or type 2 blockade, or destruction of serotonergic nerve terminals. The coadministration of tryptamine may prolong the residence period of 5-hydroxytryptamine through competition for monoamine oxidase.
authors.affiliation: Department of Zoology, University of Alberta, Edmonton, Canada.
authors.forename: B D
authors.initials: BD
authors.lastname: Sloley
authors.forename: S
authors.initials: S
authors.lastname: Orikasa
authors.forename: A A
authors.initials: AA
authors.lastname: Boulton
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D002384:Catalysis; D005473:Fluoxetine / Q000494:pharmacology; D007276:Injections, Intraventricular; D007650:Ketanserin / Q000494:pharmacology; D008297:Male; D008711:Metergoline / Q000494:pharmacology; D051379:Mice; D009474:Neurons / Q000378:metabolism; D012701:Serotonin / Q000008:administration & dosage / Q000378:metabolism*; D017367:Selective Serotonin Reuptake Inhibitors / Q000494:pharmacology; D013997:Time Factors; D014363:Tryptamines / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D005473:Fluoxetine; D007650:Ketanserin; D008711:Metergoline; D012701:Serotonin; D017367:Selective Serotonin Reuptake Inhibitors; D014363:Tryptamines; C030820:tryptamine