A receptor mechanism for methamphetamine action in dopamine transporter regulation in brain.
This study reveals a novel receptor mechanism for methamphetamine action in dopamine transporter (DAT) regulation. Trace amine-associated receptor 1 (TAAR1) is expressed in brain dopaminergic nuclei and is activated by methamphetamine in vitro. Here, we show that methamphetamine interaction with TAAR1 inhibits [(3)H]dopamine uptake, enhances or induces [(3)H]dopamine efflux, and triggers DAT internalization. In time course assays in which methamphetamine and [(3)H]dopamine were concurrently loaded into cells or synaptosomes or in pretreatment assays in which methamphetamine was washed away before [(3)H]dopamine loading, methamphetamine caused a distinct inhibition in [(3)H]dopamine uptake in TAAR1 + DAT-cotransfected cells and in wild-type mouse and rhesus monkey striatal synaptosomes. This distinct uptake inhibition was not observed in DAT-only transfected cells or in TAAR1 knockout mouse striatal synaptosomes. In [(3)H]dopamine efflux assays using the same cell and synaptosome preparations, methamphetamine enhanced [(3)H]dopamine efflux at a high loading concentration of [(3)H]dopamine (1 muM) or induced [(3)H]dopamine efflux at a low loading concentration of [(3)H]dopamine (10 nM) in a TAAR1-dependent manner. In DAT biotinylation assays using the same cell and synaptosome preparations, we observed that 1 muM methamphetamine induced DAT internalization in a TAAR1-dependent manner. All these TAAR1-mediated effects of methamphetamine were blocked by the protein kinase inhibitors H89 [N-[2-(4-bromocinnamylamino)ethyl]-5-isoquinoline] and/or 2-{8-[(dimethylamino) methyl]-6,7,8,9-tetrahydropyrido[1,2-a]indol-3-yl}-3-(1-methylindol-3-yl)maleimide (Ro32-0432), suggesting that methamphetamine interaction with TAAR1 triggers cellular phosphorylation cascades and leads to the observed effects of methamphetamine on DAT. These findings demonstrate a mediatory role of TAAR1 in methamphetamine action in DAT regulation and implicate this receptor as a potential target of therapeutics drugs for methamphetamine addiction.
New England Primate Research Center, Harvard Medical School, One Pine Hill Drive, Southborough, MA 01772, USA.
Zhihua
Z
Xie
Gregory M
GM
Miller
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D002478:Cells, Cultured; D004298:Dopamine / Q000378:metabolism; D050483:Dopamine Plasma Membrane Transport Proteins / Q000378:metabolism* / Q000502:physiology; D008253:Macaca mulatta; D008694:Methamphetamine / Q000378:metabolism* / Q000494:pharmacology*; D051379:Mice; D018345:Mice, Knockout; D011954:Receptors, Dopamine / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D000095383:Trace Amine-Associated Receptors
D004298:Dopamine; D050483:Dopamine Plasma Membrane Transport Proteins; D008694:Methamphetamine; D011954:Receptors, Dopamine; D043562:Receptors, G-Protein-Coupled; D000095383:Trace Amine-Associated Receptors