Ontogeny of multiple forms of monoamine oxidase in mouse brain.

MAO activities in mouse brain responsible for deamination of serotonin (5-HT) and p-dimethylaminobenzylamine (DAB) were found to follow different postnatal developmental patterns. MAO activity which deaminated 5-HT reached adult levels 15 days after birth. At this age the capacity of brain to deaminate DAB was only 50% of adult levels and did not develop fully until after the 45th postnatal day. Inhibitor studies with Deprenil and clorgyline indicated that the deamination of the two substrates was due to different forms of MAO and that these forms were similar to type A and type B MAO described previously in rat brain.