Trace Amines and Their Relevance to Psychiatry and Neurology: A Brief Overview

The arylalkylamines, s-phenylethylamine, m- and p-tyramine, tryptamine, m- and p-octopamine, phenylethanolamine and synephrine, have been termed trace amines because of their low absolute concentrations in the central nervous system relative to the classical neurotransmitter amines, noradrenaline, dopamine and 5-hydroxytryptamine (5-HT, serotonin). Despite being present at low concentrations, these amines have been implicated in the etiology and pharmacotherapy of several psychiatric and neurological disorders. Studies on trace amines þourished in the 1970s and 1980s, following the development of sensitive assays for these amines, and were accompanied by comprehensive electrophysiological studies and some receptor binding studies. There has been a resurgence of interest in these amines in the past decade with the discovery and cloning of a unique family of G-protein-coupled receptors, some of which are selectively activated by trace amines; these receptors have been termed trace amine, associated receptors (TAARs). The relevance of these receptors to the actions of the trace amines and to the actions of several other neurochemicals and psychotropic drugs is discussed.