Serotonin oxidation by type B MAO of rat brain

The two MAO types in rat brain can be selectively inhibited by administering intraperitoneal injections of clorgyline or pargyline in suitable doses. Brain mitochondria prepared from such animals exhibit type B or type A MAO activity, respectively. In vitro clorgyline and deprenyl dose-response curves confirmed the purity of the enzyme preparations. Specific activities and K_m values of such preparations were determined for tyramine, serotonin and benzylamine. Type B and type A MAO were found to oxidize serotonin and benzylamine. respectively, although they had low affinities. Serotonin oxidation by mitochondria prepared from clorgyline treated animals showed type B characteristics also in its heat inactivation time course.