The effects of d-amphetamine, chlordiazepoxide, alpha-flupenthixol and behavioural manipulations on choice of signalled and unsignalled delayed reinforcement in rats

Psychopharmacology (Berl). 2000 Nov;152(4):362-75. doi: 10.1007/s002130000536.


Rationale: Inability to tolerate delays to reward is an important component of impulsive behaviour, and has been suggested to reflect dysfunction of dopamine systems.

Objectives: The present experiments examined the effects of signalling a delayed, large reward on rats' ability to choose it over a small, immediate reward, and on the response to amphetamine, a dopamine receptor antagonist, and a benzodiazepine.

Methods: Three groups of Lister hooded rats were tested on a two-lever discrete-trial delayed reinforcement task in which they chose one pellet delivered immediately or four pellets delivered after a delay. This delay increased from 0 to 60 s during each session. Trials began with illumination of a houselight: in the Houselight group, this remained on during the delay and feeding period. In the No Cue group, the houselight was extinguished at the moment of choice. In the Cue group, a stimulus light was illuminated during the delay. Once trained, the rats were challenged with d-amphetamine (0.3, 1.0, 1.6 mg/kg), chlordiazepoxide (1.0, 3.2, 5.6, 10 mg/kg), alpha-flupenthixol (0.125, 0.25, 0.5 mg/kg), and various behavioural manipulations.

Results: Subjects' choice became and remained sensitive to the delay; the cue speeded learning. Amphetamine decreased choice of the large reinforcer in the No Cue group and increased it in the Cue group. alpha-Flupenthixol and chlordiazepoxide generally decreased preference for the delayed reinforcer; flupenthixol reduced the cue's effects, but chlordiazepoxide did not interact with the cue condition.

Conclusions: Signals present during a delay can enhance the ability of amphetamine to promote choice of delayed rewards.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Anxiety Agents / pharmacology
  • Chlordiazepoxide / pharmacology*
  • Choice Behavior / drug effects*
  • Conditioning, Psychological / drug effects
  • Cues
  • Dextroamphetamine / pharmacology*
  • Dopamine Agents / pharmacology
  • Feeding Methods
  • Flupenthixol / pharmacology*
  • Impulsive Behavior
  • Male
  • Models, Animal
  • Rats
  • Reaction Time / drug effects
  • Reinforcement, Psychology
  • Reproducibility of Results


  • Anti-Anxiety Agents
  • Dopamine Agents
  • Chlordiazepoxide
  • Flupenthixol
  • Dextroamphetamine