| Description: |
Trace amines, such as tyramine, beta-phenylethylamine, tryptamine and octopamine are biogenic amines present in trace levels in mammalian nervous systems []. Although some "trace amines"have clearly defined roles as neurotransmitters in invertebrates, the extent to which they function as true neurotransmitters in vertebrates has remained speculative []. Recently, a novel family of G protein-coupled receptors that share sequence similarity with the classical amine receptors has been discovered []. These trace amine associated receptors (TAAR), also known as trace amine receptors (TAR or TA), are members of the rhodopsin-like G-protein coupled receptor (GPCR) family [, ]. Some members have been shown to act as receptors for tyramine and beta-phenylethylamine, supporting a role for trace amines as neurotransmitters in vertebrates []. However, not all members have a high affinity for trace amines, some for example are olfactory receptors, which is why they are classified as trace amine associated receptors [].Since trace amine associated receptors are putative endogenous receptors for trace amines, they are of interest the pharmaceutical industry, since they are metabolic derivatives of classical biogenic amines and the psychostimulants amphetamine and methamphetamine [, , ].Trace amine-associated receptors are found in a range of taxa, but not all the members are found in all taxa [, , , ]and act as different types of receptor. In mammals, for example, TAAR1 is probably a receptor for thyronamines, decarboxylated and deiodinated metabolites of the thyroid hormones []whilst in mouse TAAR2 to TAAR9 receptors are most probably olfactory receptors for volatile amines [, ].This entry represents trace amine receptor 1 (TAAR1), it is potently activated by tyramine and beta-phenylethylamine, and displays low affinity for tryptamine, octopamine and dopamine []. TAAR1 is believed to be a key regulator of common and trace brain monoamines, and may also play some role in immune system function []. It is expressed at low to moderate levels in peripheral tissues such as the stomach, kidney and lung, and within the central nervous system is restricted predominantly to the amygdala []. |
