A role for casein kinase 1 epsilon in the locomotor stimulant response to methamphetamine

Psychopharmacology (Berl). 2009 May;203(4):703-11. doi: 10.1007/s00213-008-1417-z. Epub 2008 Dec 3.

Abstract

Rationale: We previously colocalized a quantitative trait locus (QTL) for sensitivity to the locomotor stimulant effects of methamphetamine (MA) with a QTL for expression of casein kinase 1 epsilon (Csnk1-epsilon) in the nucleus accumbens (NAc). Subsequently, we identified a single nucleotide polymorphism in CSNK1E (rs135745) that was associated with increased sensitivity to the subjective effects of d-amphetamine in healthy human subjects. Based on these results, we hypothesized that differential expression of Csnk1-epsilon causes differential sensitivity to MA-induced locomotor activity in mice.

Objective: In the present study, we used PF-670462 (PF), which is a selective inhibitor of Csnk1-epsilon, to directly evaluate the role of Csnk1-epsilon in the locomotor stimulant response to MA in male C57BL/6J mice.

Methods: We administered vehicle, PF, MA, or MA + PF, either via intraperitoneal injections or bilateral intra-NAc microinjections. We also examined Darpp-32 phosphorylation in mice receiving intraperitoneal injections.

Results: Intraperitoneal PF (20-40 mg/kg) attenuated the locomotor stimulant response to MA (2 mg/kg) without affecting baseline activity. The high dose of PF also significantly inhibited MA-induced phosphorylation of Darpp-32, providing a potential mechanism by which Csnk1-epsilon contributes to MA-induced locomotor activity. Furthermore, microinjection of PF (5 microg/side) into the NAc completely blocked the locomotor stimulant response to MA (2.5 microg/side) without affecting baseline activity.

Conclusions: These results provide direct evidence that Csnk1-epsilon is crucial for the locomotor stimulant response to a moderate dose of MA and suggest that genetic polymorphisms affecting Csnk1-epsilon expression or function could influence sensitivity to amphetamines in both mice and humans.

Publication types

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

MeSH terms

  • Animals
  • Casein Kinase Iepsilon / antagonists & inhibitors
  • Casein Kinase Iepsilon / genetics*
  • Central Nervous System Stimulants / pharmacology*
  • Dopamine and cAMP-Regulated Phosphoprotein 32 / metabolism
  • Dose-Response Relationship, Drug
  • Injections, Intraperitoneal
  • Male
  • Methamphetamine / pharmacology*
  • Mice
  • Mice, Inbred C57BL
  • Motor Activity / drug effects*
  • Nucleus Accumbens / drug effects
  • Nucleus Accumbens / metabolism
  • Phosphorylation
  • Polymorphism, Single Nucleotide
  • Pyrimidines / pharmacology
  • Quantitative Trait Loci

Substances

  • Central Nervous System Stimulants
  • Dopamine and cAMP-Regulated Phosphoprotein 32
  • Ppp1r1b protein, mouse
  • Pyrimidines
  • Methamphetamine
  • PF-670462
  • Casein Kinase Iepsilon