Trace Amine-Associated Receptors

Trace amine-associated receptors (TAARs) are a class of G-protein-coupled receptors, identified in human (six subtypes) and other vertebrates and invertebrates. TAAR1 is a receptor for tyramine, β-phenylethylamine, octopamine, tryptamine, and 3-iodothyronamine, a thyroid hormone derivative, present in the brain at nanomolar concentrations. TAAR1 is expressed in many brain regions, and in vitro it is activated by amphetamines and other psychotropic agents. Pharmacological and behavioral observations in TAAR1 knockout mice suggest that TAAR1 stimulation reduces monoaminergic signaling and modulates the neurochemical and behavioral effects of amphetamines and cocaine. Other TAARs, particularly TAAR6, are expressed in the brain. Notably, TAAR6 and TAAR2 polymorphisms have been associated with psychosis. All TAAR subtypes different from TAAR1 are extensively expressed in olfactory epithelium and are thought to represent a specific class of olfactory receptors.