In-vivo pharmacology of Trace-Amine Associated Receptor 1
EUROPEAN JOURNAL OF PHARMACOLOGY
Authors: Lam, Vincent M.; Espinoza, Stefano; Gerasimov, Andrey S.; Gainetdinov, Raul R.; Salahpour, Ali
Abstract
Trace-amines (TAs) are endogenous amines that are implicated in several physiological processes including modulation of aminergic neurotransmission. These compounds exert their effect by activating a class of G protein-coupled receptors termed Trace-Amine Associated Receptors (TAARs), where TAAR1 is the only human receptor that has been shown to bind endogenous TAs. Most of the studies have focused on studying the role of TAAR1 on modulation of the dopamine transmission. These studies indicate that TAAR1 is a negative regulator of dopamine transmission making TAAR1 a novel target for neuropsychiatric disorders that arises from dopamine dysfunction such as schizophrenia. This review discusses the unique pharmacology of TAAR1 with the major focus on the physiological role of TAAR1 and its modulation of dopamine transmission. (C) 2015 Elsevier B.V. All rights reserved.
In Vitro Characterization of Psychoactive Substances at Rat, Mouse, and Human Trace Amine-Associated Receptor 1
JOURNAL OF PHARMACOLOGY AND EXPERIMENTAL THERAPEUTICS
Authors: Simmler, Linda D.; Buchy, Daniele; Chaboz, Sylvie; Hoener, Marius C.; Liechti, Matthias E.
Abstract
Trace amine-associated receptor 1 (TAAR1) has been implicated in the behavioral effects of amphetamine-type stimulant drugs in rodents. TAAR1 has also been suggested as a target for novel medications to treat psychostimulant addiction. We previously reported that binding affinities at TAAR1 can differ between structural analogs of psychostimulants, and species differences have been observed. In this study, we complement our previous findings with additional substances and the determination of functional activation potencies. In summary, we present here pharmacological in vitro profiles of 101 psychoactive substances at human, rat, and mouse TAAR1. p-Tyramine, beta-phenylethylamine, and tryptamine were included as endogenous comparator compounds. Functional cAMP measurements and radioligand displacement assays were conducted with human embryonic kidney 293 cells that expressed human, rat, or mouse TAAR1. Most amphetamines, phenethylamine, and aminoindanes exhibited potentially physiologically relevant rat and mouse TAAR1 activation (EC50 < 5 mu M) and showed full or partial (E-max < 80%) agonist properties. Cathinone derivatives, including mephedrone and methylenedioxypyrovalerone, exhibited weak (EC50 - 5-10 mu M) to negligible (EC50 > 10 mu M) binding properties at TAAR1. Pipradrols, including methylphenidate, exhibited no affinity for TAAR1. We found considerable species differences in activity at TAAR1 among the highly active ligands, with a rank order of rat > mouse > human. This characterization provides information about the pharmacological profile of psychoactive substances. The species differences emphasize the relevance of clinical studies to translationally complement rodent studies on the role of TAAR1 activity for psychoactive substances.