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METABOLISM OF BIOGENIC AMINES IN NEUROBLASTOMA AND GLIOMA CELLS IN CULTURE 1
Author(s) -
Skaper S. D.,
Adelson G. L.,
Seegmiller J. E.
Publication year - 1976
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.1471-4159.1976.tb00309.x
Subject(s) - monoamine oxidase , neuroblastoma , endocrinology , medicine , glioma , tyramine , cell culture , tryptamine , catecholamine , serotonin , monoamine oxidase a , biology , acetylcholinesterase , norepinephrine , neurotransmitter , chemistry , biochemistry , dopamine , enzyme , cancer research , receptor , central nervous system , genetics
— The kinetic parameters of monoamine oxidase (MAO; E.C 1.4.3.4) and catechol‐ O ‐methyl‐transferase (COMT; EC 2.1.1.6) were evaluated in extracts of adrenergic and non‐adrenergic mouse neuroblastoma cells and in rat glioma cells. Using the naturally‐occurring substrates tyramine, tryptamine, serotonin and norepinephrine, the affinity of MAO for a given substrate was independent of the presence of the catecholaminergic pathway or cell type used, with apparent K m values ranging from 8–14 μM for tryptamine to 510–580 μM for norepinephrine. The MAO activity in glioma cells was substantially greater than in either neuroblastoma clone, but V max values varied little with substrate among cell lines. Both the neuronal and glial COMT had a similar K m for I‐norepinephrine (200μM); the corresponding V max values were also similar among the different cell lines, but represented only 2–10% of the maximal MAO activity. Neuroblastoma and glioma cells, when grown from early logarithmic to stationary phase, showed no significant changes in specific activity of either MAO or COMT. Growth of cells for 3 days with 1 mM‐N 6 ,O 2′ ‐dibutyryl adenosine‐3′,5′‐cyclic monophosphate resulted in no marked change in either MAO or COMT activity. These results suggest that in neurons neither MAO nor COMT plays a major role in the type of transmitter inactivation that is analogous to that of acetylcholinesterase in cholinergic synapses. The occurrence of considerable MAO and acetylcholinesterase activities in glioma cells may indicate a role for these cells in neurotransmitter inactivation.