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THE UPTAKE AND SUBCELLULAR DISTRIBUTION OF AROMATIC AMINES IN THE BRAIN OF THE RAT 1
Author(s) -
Baldessarini R. J.,
Vogt Marcella
Publication year - 1971
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1971.tb00208.x
Subject(s) - octopamine (neurotransmitter) , tyramine , metaraminol , reserpine , chemistry , norepinephrine , monoamine oxidase , catecholamine , medicine , endocrinology , biogenic amine , free nerve ending , dopamine , biochemistry , neurotransmitter , serotonin , biology , enzyme , receptor , blood pressure
— The hydroxylated phenylethylamines p ‐tyramine, m ‐tyramine, octopamine, metaraminol and norepinephrine were accumulated by homogenates of rat brain much more vigorously than β‐phenethylamine or amphetamine. The affinity concentrations ( K m ) for initial (5‐min) uptake by homogenates of whole brain were 0.5, 3 and 6 μM for DL‐norepine‐phrine, p‐tyramine and DL‐octopamine, respectively. The uptake of these three hydroxylated compounds was much more vigorous in striatal tissue than in cortical tissue, and in both tissues the rate of uptake decreased in the sequence: norepinephrine > tyramine > octopamine. The uptake of these three substances was inhibited by reduced temperature, by lack of glucose, by CN‐ and DNP, and by desmethylimipramine, cocaine and ouabain. The uptake of norepinephrine and octopamine appeared to require Na + . Pretreatment of rats with reserpine or 6‐hydroxydopamine decreased the ability of brain to take up norepinephrine or octopamine. Previously accumulated labelled phenylethylamines migrated in sucrose density gradients with a peak of radioactivity corresponding to an equilibrium position of catecholamine‐containing nerve endings. The magnitude of the retention of [ 3 H]amine in this synaptosornal peak decreased in the order: norepinephrine > octopamine > tyramine. The accumulated amines were released by sonic, osmotic and thermal stresses which disrupt neuronal membranes. The presence of a β‐hydroxyl group appeared to protect amines from destruction by monoamine oxidase, presumably by virtue of uptake in presynaptic storage vesicles. During superfusion, tyramine and metaraminol appeared to displace [ 3 H]norepinephrine from binding sites in brain slices.