Methamphetamine and HIV-1-induced neurotoxicity: role of trace amine associated receptor 1 cAMP signaling in astrocytes

Neuropharmacology. 2014 Oct;85:499-507. doi: 10.1016/j.neuropharm.2014.06.011. Epub 2014 Jun 17.

Abstract

Methamphetamine (METH) is abused by about 5% of the United States population with approximately 10-15% of human immunodeficiency virus-1 (HIV-1) patients reporting its use. METH abuse accelerates the onset and severity of HIV-associated neurocognitive disorders (HAND) and astrocyte-induced neurotoxicity. METH activates G-protein coupled receptors such as trace amine associated receptor 1 (TAAR1) increasing intracellular cyclic adenosine monophosphate (cAMP) levels in presynaptic cells of monoaminergic systems. In the present study, we investigated the effects of METH and HIV-1 on primary human astrocyte TAAR1 expression, function and glutamate clearance. Our results demonstrate combined conditions increased TAAR1 mRNA levels 7-fold and increased intracellular cAMP levels. METH and beta-phenylethylamine (β-PEA), known TAAR1 agonists, increased intracellular cAMP levels in astrocytes. Further, TAAR1 knockdown significantly reduced intracellular cAMP levels in response to METH/β-PEA, indicating signaling through astrocyte TAAR1. METH±HIV-1 decreased excitatory amino acid transporter-2 (EAAT-2) mRNA and significantly decreased glutamate clearance. RNA interference for TAAR1 prevented METH-mediated decreases in EAAT-2. TAAR1 knockdown significantly increased glutamate clearance, which was further heightened significantly by METH. Moreover, TAAR1 overexpression significantly decreased EAAT-2 levels and glutamate clearance that were further reduced by METH. Taken together, our data show that METH treatment activated TAAR1 leading to intracellular cAMP in human astrocytes and modulated glutamate clearance abilities. Furthermore, molecular alterations in astrocyte TAAR1 levels correspond to changes in astrocyte EAAT-2 levels and function. To our knowledge this is the first report implicating astrocyte TAAR1 as a novel receptor for METH during combined injury in the context of HAND.

Keywords: Astrocytes; Human immunodeficiency virus-1; Methamphetamine; Trace amine associated receptor 1; cAMP.

Publication types

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

MeSH terms

  • Astrocytes / drug effects
  • Astrocytes / physiology*
  • Astrocytes / virology
  • Cells, Cultured
  • Central Nervous System Agents / pharmacology*
  • Colforsin / pharmacology
  • Cyclic AMP / metabolism
  • Dose-Response Relationship, Drug
  • Gene Knockdown Techniques
  • Glutamate Plasma Membrane Transport Proteins / metabolism
  • Glutamic Acid / metabolism
  • HIV Infections / physiopathology*
  • HIV-1 / physiology*
  • Humans
  • Methamphetamine / pharmacology*
  • Phenethylamines / pharmacology
  • RNA Interference
  • RNA, Messenger / metabolism
  • Receptors, G-Protein-Coupled / agonists*
  • Receptors, G-Protein-Coupled / genetics
  • Receptors, G-Protein-Coupled / metabolism

Substances

  • Central Nervous System Agents
  • Glutamate Plasma Membrane Transport Proteins
  • Phenethylamines
  • RNA, Messenger
  • Receptors, G-Protein-Coupled
  • SLC1A2 protein, human
  • Colforsin
  • phenethylamine
  • Glutamic Acid
  • Methamphetamine
  • Cyclic AMP
  • Trace amine-associated receptor 1