Functional interactions of 2-phenylethylamine and of tryptamine with brain catecholamines: implications for psychotherapeutic drug action.

1. The relevance of trace amine research is outlined for PEA and T in the context of psychotherapeutic drug action, particularly in relation to the actions of MAO-inhibitor antidepressant drugs. 2. Evidence for the neuronal localization of these amines and their relationship to brain catecholamines is discussed with respect to possible co-localization with DA and their distribution within the nigro-striatal/striato-nigral system. 3. The results of recent experiments assessing the behavioural effects of prodrugs for PEA and T are described. The interactions of these compounds with MAO inhibitors are assessed and the actions of PEA prodrugs are discussed in relation to brain DA systems. 4. Recent evidence for functional decreases in beta-adrenergic receptors following chronic administration of MAO inhibitors is outlined. The lack of association of such effects with the percentage of MAO inhibition observed after these treatments indicates influences of these compounds (or metabolites) on factors other than MAO activity as mediators of these effects. The possible role of PEA (as a metabolite of PLZ) in this context is proposed. The possible involvement of PEA in emergent changes in beta-adrenergic receptors induced by chronic antidepressant drugs is hypothesized in relation to ongoing research.