Developmental changes in the activity and substrate specificities of mouse brain monoamine oxidase.
Developmental changes in monoamine oxidase (MAO) activity in the mouse brain were investigated with the substrates beta-phenylethylamine (PEA), tryptamine, and 5-hydroxytryptamine (5-HT). In the newborn brain, MAO activity towards PEA was found to be much lower than the adult and to be inhibited by clorgyline in a double-sigmoidal fashion. The inhibition curve shifted to a single-sigmoidal pattern with age. MAO activity towards 5-HT as substrate was inhibited by 90% and in a single-sigmoidal manner by clorgyline throughout the postnatal life. Lineweaver-Burk plots with PEA as substrate presented two linear lines (apparent Km: 28.6 and 4.1 microM) for the newborn and one line (apparent Km: 11.4 microM) for the adult, respectively. The plot with high Km value for the newborn brain disappeared in a clorgyline-treated preparation. These findings suggest that age-dependent alterations in the ratio of MAO-A/MAO-B activity affect the substrate specificity of the enzyme.
D000818:Animals; D001921:Brain / Q000201:enzymology / Q000254:growth & development*; D003010:Clorgyline / Q000494:pharmacology; D007527:Isoenzymes / Q000378:metabolism; D007700:Kinetics; D051379:Mice; D008809:Mice, Inbred C3H; D008995:Monoamine Oxidase / Q000378:metabolism*; D008996:Monoamine Oxidase Inhibitors / Q000494:pharmacology; D010627:Phenethylamines / Q000494:pharmacology; D012701:Serotonin / Q000378:metabolism; D013379:Substrate Specificity
D007527:Isoenzymes; D008996:Monoamine Oxidase Inhibitors; D010627:Phenethylamines; C029261:phenethylamine; D012701:Serotonin; D008995:Monoamine Oxidase; D003010:Clorgyline