title: MAO activity in serotonergic endings of rat major cerebral arteries.
abstract: The present work studies the existence of monoamine oxidase (MAO) activity in serotonergic endings present in rat major cerebral arteries. Enzymatic activity was appraised in vivo by serotonin (5-HT) accumulation or 5-hydroxyindole acetic acid (5-HIAA) disappearance with time after systemic administration of MAO inhibitors. Pargyline (75 mg/Kg, ip) brought about significant 5-HT increase and 5-HIAA decrease in major cerebral arteries 30 and 60 min after its administration. Clorgyline (75 mg/Kg, ip) also induced 5-HT enhancement and 5-HIAA decline in these arteries 30 and 60 min after its injection. However, treatment with deprenyl (75 mg/Kg, ip) only evoked a significant 5-HT increase at 60 min. When either clorgyline (5 mg/Kg, ip) or deprenyl (5 mg/Kg, ip) were administered 5-HT and 5-HIAA levels remained unaffected. Two weeks after performing electrolytical lesion of dorsal raphe nucleus and 60 min after clorgyline (75 mg/Kg, ip) injection 5-HT and 5-HIAA levels appeared significantly reduced in cerebral arteries and striatum when compared to sham-lesioned controls. These results suggest that MAO-A isoform acting on endogenous 5-HT is present in rat major cerebral arteries and is located in nerve endings of fibers arising from dorsal raphe nucleus.
authors.affiliation: Departamento de Fisiología, Facultad de Medicina, Universidad Autónoma de Madrid, Arzobispo Morcillo, 2, 28029 Madrid, Spain.
authors.forename: A L
authors.initials: AL
authors.lastname: López de Pablo
authors.forename: M
authors.initials: M
authors.lastname: Ajubita
authors.forename: M C F
authors.initials: MC
authors.lastname: Criado
authors.forename: E J
authors.initials: EJ
authors.lastname: Marco
mesh_terms: D000818:Animals; D002536:Cerebral Arteries / Q000201:enzymology* / Q000294:innervation; D008297:Male; D008995:Monoamine Oxidase / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000378:metabolism*
chemical_list: D012701:Serotonin; D008995:Monoamine Oxidase