Trace amine-associated receptor 1 is a modulator of the dopamine transporter

J Pharmacol Exp Ther. 2007 Apr;321(1):128-36. doi: 10.1124/jpet.106.117382. Epub 2007 Jan 18.

Abstract

Trace amine-associated receptor 1 (TAAR1) is a G protein-coupled receptor activated by a broad range of monoamines and amphetamine-related psychostimulants. Recent studies demonstrated wide distribution of TAAR1 in brain, coexpression of TAAR1 with dopamine transporter (DAT) in a subset of dopamine neurons in both mouse and rhesus monkey substantia nigra, and monoamine transporter-modulated activation. This study explored whether TAAR1 could influence DAT-mediated dopamine uptake and efflux. Rhesus monkey TAAR1 expressed with DAT in human embryonic kidney 293 cells was dose-dependently activated by dopamine or (+)-methamphetamine. This activation resulted in large cAMP increases and a transient reduction in [3H]dopamine accumulation within the cells, which was similar to the effect of dopamine D1 receptor (D1) or forskolin treatment. In addition, TAAR1 effects on dopamine uptake could be blocked by a protein kinase A or protein kinase C (PKC) inhibitor. [3H]Dopamine efflux assays performed in Dulbecco's modified Eagle's medium displayed a TAAR1-dependent spontaneous [3H]dopamine efflux that was dose-dependently augmented by dopamine or (+)-methamphetamine and that was blocked by either methylphenidate or a PKC inhibitor. DAT cells in Krebs-HEPES buffer had an apparent spontaneous [3H]dopamine loss, but it could not be blocked by either methylphenidate or a PKC inhibitor. Taken together, this study provides evidence that TAAR1 is involved in functional regulation of DAT and suggests that TAAR1 is a potentially important target for therapeutics for methamphetamine addiction.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Cell Line
  • Colforsin / pharmacology
  • Cyclic AMP / metabolism
  • Cyclic AMP-Dependent Protein Kinases / antagonists & inhibitors
  • Cyclic AMP-Dependent Protein Kinases / metabolism
  • Dopamine / metabolism
  • Dopamine / pharmacology
  • Dopamine Plasma Membrane Transport Proteins / physiology*
  • Dopamine Uptake Inhibitors / pharmacology
  • Dose-Response Relationship, Drug
  • Enzyme Inhibitors / pharmacology
  • Humans
  • Indoles / pharmacology
  • Luciferases / genetics
  • Macaca mulatta
  • Methamphetamine / pharmacology
  • Methylphenidate / pharmacology
  • Phosphorylation
  • Protein Kinase C / antagonists & inhibitors
  • Protein Kinase C / metabolism
  • Pyrroles / pharmacology
  • Receptors, G-Protein-Coupled / physiology*
  • Stimulation, Chemical

Substances

  • Dopamine Plasma Membrane Transport Proteins
  • Dopamine Uptake Inhibitors
  • Enzyme Inhibitors
  • Indoles
  • Pyrroles
  • Receptors, G-Protein-Coupled
  • Ro 32-0432
  • Colforsin
  • Methylphenidate
  • Methamphetamine
  • Cyclic AMP
  • Luciferases
  • Cyclic AMP-Dependent Protein Kinases
  • Protein Kinase C
  • Dopamine
  • Trace amine-associated receptor 1