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Names | |
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Preferred IUPAC name 4-(2-Aminoethyl)-2-methoxyphenol | |
Other names 3-O-Methyldopamine | |
Identifiers | |
3D model (JSmol) | |
ChEBI | |
ChemSpider | |
ECHA InfoCard | 100.122.789 |
MeSH | 3-methoxytyramine |
PubChem CID | |
UNII | |
CompTox Dashboard (EPA) | |
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Properties | |
C9H13NO2 | |
Molar mass | 167.21 g/mol |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
3-Methoxytyramine (3-MT), also known as 3-methoxy-4-hydroxyphenethylamine, is a human trace amine and the major metabolite of the monoamine neurotransmitter dopamine. [1] [2] It is formed by the introduction of a methyl group to dopamine by the enzyme catechol-O-methyltransferase (COMT). 3-MT can be further metabolized by the enzyme monoamine oxidase (MAO) to form homovanillic acid (HVA), which is then typically excreted in the urine.
3-Methoxytyramine occurs naturally in the prickly pear cactus (genus Opuntia), [3] and is in general widespread throughout the Cactaceae. [4] It has also been found in crown gall tumors on Nicotiana sp. [5]
In humans, 3-methoxytyramine is a trace amine that occurs as a metabolite of dopamine. [1]
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Originally thought to be physiologically inactive, 3-MT was subsequently found to act as an agonist of the rodent and human TAAR1. [1] [9] [2] 3-MT can induce weak hyperlocomotion in mice and this effect is partially attenuated in TAAR1 knockout mice. [2] [10]
The data support the hypothesis that TAAR1 inhibits locomotor activity via a down-modulation of dopamine neurotransmission (Lindemann et al. 2008) and that the overruling effect of blocking TAAR1 is a net increase in the firing rate of DA neurons (Bradaia et al. 2009). However, a more recent study by Sotnikova et al. (2010) reports that the major extracellular metabolite of dopamine, 3-methoxytyramine, which is an agonist at rat TAAR1 (Bunzow et al. 2001), can induce mild hyperactivity in normal mice and a complex set of abnormal involuntary movements in normal mice acutely depleted of dopamine, and that these effects were attenuated in TAAR1 knockout mice. These data suggest that TAAR1 activation may stimulate locomotor activity. Collectively, the data illustrate a complexity of TAAR1 neurobiology that is still not fully understood.