Salvinorin A regulates dopamine transporter function via a kappa opioid receptor and ERK1/2-dependent mechanism

Neuropharmacology. 2014 Nov;86:228-40. doi: 10.1016/j.neuropharm.2014.07.016. Epub 2014 Aug 10.

Abstract

Salvinorin A (SalA), a selective κ-opioid receptor (KOR) agonist, produces dysphoria and pro-depressant like effects. These actions have been attributed to inhibition of striatal dopamine release. The dopamine transporter (DAT) regulates dopamine transmission via uptake of released neurotransmitter. KORs are apposed to DAT in dopamine nerve terminals suggesting an additional target by which SalA modulates dopamine transmission. SalA produced a concentration-dependent, nor-binaltorphimine (BNI)- and pertussis toxin-sensitive increase of ASP(+) accumulation in EM4 cells coexpressing myc-KOR and YFP-DAT, using live cell imaging and the fluorescent monoamine transporter substrate, trans 4-(4-(dimethylamino)-styryl)-N-methylpyridinium) (ASP(+)). Other KOR agonists also increased DAT activity that was abolished by BNI pretreatment. While SalA increased DAT activity, SalA treatment decreased serotonin transporter (SERT) activity and had no effect on norepinephrine transporter (NET) activity. In striatum, SalA increased the Vmax for DAT mediated DA transport and DAT surface expression. SalA up-regulation of DAT function is mediated by KOR activation and the KOR-linked extracellular signal regulated kinase-½ (ERK1/2) pathway. Co-immunoprecipitation and BRET studies revealed that DAT and KOR exist in a complex. In live cells, DAT and KOR exhibited robust FRET signals under basal conditions. SalA exposure caused a rapid and significant increase of the FRET signal. This suggests that the formation of KOR and DAT complexes is promoted in response to KOR activation. Together, these data suggest that enhanced DA transport and decreased DA release resulting in decreased dopamine signalling may contribute to the dysphoric and pro-depressant like effects of SalA and other KOR agonists.

Keywords: Dopamine transporter; Dysphoric; Kappa opioid receptor; Pro-depressant; Salvinorin A; Serotonin transporter; Trafficking.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Membrane / drug effects
  • Cell Membrane / metabolism
  • Corpus Striatum / drug effects
  • Corpus Striatum / metabolism
  • Diterpenes, Clerodane / pharmacology*
  • Dopamine / metabolism
  • Dopamine Agents / pharmacology*
  • Dopamine Plasma Membrane Transport Proteins / metabolism*
  • HEK293 Cells
  • Humans
  • MAP Kinase Signaling System / drug effects*
  • MAP Kinase Signaling System / physiology
  • Norepinephrine Plasma Membrane Transport Proteins / metabolism
  • Receptors, Opioid, kappa / agonists
  • Receptors, Opioid, kappa / metabolism*
  • Serotonin Plasma Membrane Transport Proteins / metabolism
  • p38 Mitogen-Activated Protein Kinases / metabolism

Substances

  • Diterpenes, Clerodane
  • Dopamine Agents
  • Dopamine Plasma Membrane Transport Proteins
  • Norepinephrine Plasma Membrane Transport Proteins
  • Receptors, Opioid, kappa
  • SLC6A2 protein, human
  • SLC6A4 protein, human
  • Serotonin Plasma Membrane Transport Proteins
  • p38 Mitogen-Activated Protein Kinases
  • salvinorin A
  • Dopamine