Dopamine metabolism in human brain: effect of monoamine oxidase inhibition in vitro by (-)deprenyl and (+) and (-) tranylcypromine.

The effects of the monoamine oxidase inhibitors (-)deprenyl and (+)-and (-)tranylcypromine on dopamine oxidation in human caudate have been investigated. Oxidation of dopamine has been found to exhibit both (-)deprenyl-sensitive and -insensitive components. The tranylcypromine isomers are both more sensitive towards dopamine than 5-hydroxytryptamine oxidation, (+) isomer being the more effective of the two. These results are discussed in terms of the in vivo action of the drugs and their therapeutic value.