Effects of nucleus accumbens amphetamine administration on performance in a delay discounting task

Behav Brain Res. 2017 Mar 15:321:130-136. doi: 10.1016/j.bbr.2017.01.001. Epub 2017 Jan 3.

Abstract

Chronic administration of cocaine can cause pronounced and enduring cognitive alterations such as increases in impulsive choice. Chronic cocaine can also result in enhanced dopamine (DA) release in the nucleus accumbens (NAc) in response to reward-related cues. It is possible that this enhanced DA release in the NAc is a mechanism by which cocaine increases impulsive choice. To date, however, the specific role of DA in the NAc in impulsive choice is unclear. To begin to address this, rats received acute microinjections of the indirect DA agonist amphetamine directly into the NAc prior to testing in a delay discounting task in which rats chose between a small, immediate and a large, delayed food reward. When delays to the large reward increased within test sessions, amphetamine increased choice of the large reward. When delays decreased within test sessions, however, amphetamine decreased choice of the large reward. These findings suggest that, rather than specifically mediating impulsive choice, DA neurotransmission in the NAc is necessary for flexible adaptation of choice strategies in the presence of shifting reward contingencies. These results further indicate that enhancements in NAc DA release likely do not account for lasting increases in impulsive choice caused by chronic cocaine.

Keywords: Amphetamine; Delay discounting; Dopamine; Impulsive choice; Intertemporal choice; Nucleus accumbens.

Publication types

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

MeSH terms

  • Amphetamine / pharmacology*
  • Analysis of Variance
  • Animals
  • Delay Discounting / drug effects*
  • Delay Discounting / physiology
  • Dopamine / metabolism
  • Dopamine Agents / pharmacology*
  • Dose-Response Relationship, Drug
  • Impulsive Behavior / drug effects
  • Impulsive Behavior / physiology
  • Male
  • Microinjections
  • Nucleus Accumbens / drug effects*
  • Nucleus Accumbens / metabolism
  • Psychological Tests
  • Rats, Long-Evans
  • Reward

Substances

  • Dopamine Agents
  • Amphetamine
  • Dopamine