Conjugates of biogenic amines in ventriculocisternal perfusates of conscious African green monkeys.
To determine the importance of conjugation relative to alternate metabolic pathways for the inactivation of catecholamines and serotonin, free and conjugated norepinephrine, dopamine and serotonin, together with the acid metabolites homovanillic acid and 5-hydroxyindoleacetic acid, were measured in ventriculocisternal perfusions in awake African green monkeys. Measurements were made of endogenous transmitters and their metabolites using high performance liquid chromatography with electrochemical detection. Efflux of amines and metabolites was measured both under conditions of spontaneous overflow and during release evoked by 40 mM K+ or by 5 X 10(-5) M amphetamine. Conjugated amines were of greater importance under basal conditions than during evoked release. Although more conjugated amines were produced in African green monkey than has been previously detected in other species, conjugation was still minor relative to O-methylation and oxidative deamination. When nomifensine (5 X 10(-5) M), a blocker of neuronal uptake of dopamine, was added to perfusion fluids, the efflux of free dopamine was increased. Efflux of conjugated dopamine was not decreased in the presence of nomifensine, suggesting that conjugation did not occur subsequent to reuptake of transmitter into dopaminergic neurons. Evidence is also presented that different enzymes are responsible for the conjugation of catecholamines and serotonin.
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D000818:Animals; D001679:Biogenic Amines / Q000134:cerebrospinal fluid / Q000378:metabolism*; D001921:Brain / Q000378:metabolism*; D002522:Chlorocebus aethiops; D003913:Dextroamphetamine / Q000494:pharmacology; D004298:Dopamine / Q000378:metabolism; D005260:Female; D009627:Nomifensine / Q000494:pharmacology; D009638:Norepinephrine / Q000378:metabolism; D011188:Potassium / Q000494:pharmacology; D012701:Serotonin / Q000378:metabolism
D001679:Biogenic Amines; D009627:Nomifensine; D012701:Serotonin; D011188:Potassium; D003913:Dextroamphetamine; D004298:Dopamine; D009638:Norepinephrine