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On the Mechanism of the Involvement of Monoamine Oxidase in Catecholamine‐Stimulated Prostaglandin Biosynthesis in Particulate Fraction of Rat Brain Homogenates: Role of Hydrogen Peroxide
Author(s) -
Seregi András,
Serfözö Péter,
Mergl Zsuzsanna,
Schaefer András
Publication year - 1982
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.1471-4159.1982.tb10849.x
Subject(s) - pargyline , chemistry , catecholamine , catalase , monoamine oxidase , dopamine , biochemistry , metabolite , alpha (finance) , stimulation , endocrinology , hydrogen peroxide , biosynthesis , prostaglandin , medicine , enzyme , biology , construct validity , nursing , patient satisfaction
The mechanism of involvement of monoamine oxidase (MAO) in catecholamine‐stimulated prostaglandin (PG) biosynthesis was studied in the particulate fraction of rat brain homogenates. High concentrations of either noradrenaline (NA) or dopamine (DA) stimulated effectively PGF 2α formation. The same amount of 2‐phenylethylamine (PEA) acted similarly, provided that it was administered together with a catecholamine analogue or metabolite possessing the 3,4‐dihydroxyphenyl nucleus–3, 4‐dihydroxyphenylalanine (DOPA), 3,4‐dihydroxyphenylacetic acid (DOPAC), 3,4‐dihydroxyphenyl‐glycol (DOPEG), 3,4‐dihydroxyphenylacetaldehyde (DOPAL), or α‐methylnoradrenaline (α‐met‐NA)–or with SnCl 2 . In the absence of PEA, these compounds were ineffective with regard to stimulation of PGF 2α formation. Catalase, pargyline, or indomethacin abolished completely PGF 2α formation elicited either by catecholamines or by PEA plus a 3,4‐dihydroxyphenyl compound or SnCl 2 . With regard to the stimulation of PGF 2α formation in the presence of α‐met‐NA, PEA could be replaced by H 2 O 2 , generated by the glucose oxidase(GOD)‐glucose system. The effect of H 2 O 2 was inhibited by indomethacin or catalase, but pargyline was ineffective. It is assumed that catecholamines play a dual role in the activation of PG biosynthesis in brain tissue. During the enzymatic decomposition of catecholamines MAO produces H 2 O 2 , which stimulates endoperoxide synthesis. Simultaneously, catecholamines as hydrogen donors promote the nonenzymatic transformation of endoperoxides into PGF 2α . The possible physiological importance of these findings is discussed.