trace amine trace amine trace amines are an endogenous group of trace amine-associated receptor 1 (taar1) agonists – and hence, monoaminergic neuromodulators – that are structurally and metabolically related to classical monoamine neurotransmitters. compared to the classical monoamines, they are present in trace concentrations. they are distributed heterogeneously throughout the mammalian brain and peripheral nervous tissues and exhibit high rates of metabolism. although they can be synthesized within parent monoamine neurotransmitter systems, there is evidence that suggests that some of them may comprise their own independent neurotransmitter systems. trace aminedrug classphenethylamine skeletonclass identifiersmechanism of actionreceptor agonistbiological targethuman trace amine-associated receptor 1chemical classendogenous amines with trace occurrence(nanograms or less per gram of brain tissue)