Format

Send to

Choose Destination
J Pharmacol Exp Ther. 2019 Oct;371(1):36-44. doi: 10.1124/jpet.119.258970. Epub 2019 Jul 18.

The Role of Biogenic Amine Transporters in Trace Amine-Associated Receptor 1 Regulation of Methamphetamine-Induced Neurotoxicity.

Author information

1
Research Service, VA Portland Health Care System, Portland, Oregon (N.B.M., T.J.P., A.J.); and Departments of Behavioral Neuroscience (N.B.M., T.J.P., A.J.) and Psychiatry (A.J.), and The Methamphetamine Abuse Research Center (T.J.P., A.J.), Oregon Health & Science University, Portland, Oregon.
2
Research Service, VA Portland Health Care System, Portland, Oregon (N.B.M., T.J.P., A.J.); and Departments of Behavioral Neuroscience (N.B.M., T.J.P., A.J.) and Psychiatry (A.J.), and The Methamphetamine Abuse Research Center (T.J.P., A.J.), Oregon Health & Science University, Portland, Oregon janowsky@ohsu.edu.

Abstract

Methamphetamine (MA) impairs vesicular monoamine transporter 2 (VMAT2) and dopamine transporter (DAT) function and expression, increasing intracellular DA levels that lead to neurotoxicity. The trace amine-associated receptor 1 (TAAR1) is activated by MA, but when the receptor is not activated, MA-induced neurotoxicity is increased. To investigate interactions among TAAR1, VMAT2, and DAT, transporter function and expression were measured in transgenic Taar1 knockout (KO) and wild-type (WT) mice 24 hours following a binge-like regimen (four intraperitoneal injections, 2 hours apart) of MA (5 mg/kg) or the same schedule of saline treatment. Striatal synaptosomes were separated by fractionation to examine the function and expression of VMAT2 localized to cytosolic and membrane-associated vesicles. DAT was measured in whole synaptosomes. VMAT2-mediated [3H]DA uptake inhibition was increased in Taar1 KO mice in synaptosomal and vesicular fractions, but not the membrane-associated fraction, compared with Taar1 WT mice. There was no difference in [3H]dihydrotetrabenazine binding to the VMAT2 or [125I]RTI-55 binding to the DAT between genotypes, indicating activation of TAAR1 does not affect VMAT2 or DAT expression. There was also no difference between Taar1 WT and KO mice in DAT-mediated [3H]DA uptake inhibition following in vitro treatment with MA. These findings provide the first evidence of a TAAR1-VMAT2 interaction, as activation of TAAR1 mitigated MA-induced impairment of VMAT2 function, independently of change in VMAT2 expression. Additionally, the interaction is localized to intracellular VMAT2 on cytosolic vesicles and did not affect expression or function of DAT in synaptosomes or VMAT2 at the plasmalemmal surface, i.e., on membrane-associated vesicles. SIGNIFICANCE STATEMENT: Methamphetamine stimulates the G protein-coupled receptor TAAR1 to affect dopaminergic function and neurotoxicity. Here we demonstrate that a functional TAAR1 protects a specific subcellular fraction of VMAT2, but not the dopamine transporter, from methamphetamine-induced effects, suggesting new directions in pharmacotherapeutic development for neurodegenerative disorders.

PMID:
31320495
PMCID:
PMC6750185
[Available on 2020-10-01]
DOI:
10.1124/jpet.119.258970

Supplemental Content

Full text links

Icon for HighWire
Loading ...
Support Center