Competition between the conditioned rewarding effects of cocaine and novelty

Behav Neurosci. 2008 Feb;122(1):140-50. doi: 10.1037/0735-7044.122.1.140.

Abstract

Access to novelty might provide an alternative learning history that competes with conditioned drug reward. We tested this suggestion in rats using a place conditioning procedure with cocaine and novelty. In Experiment 1, rats were conditioned with cocaine to prefer one side of an apparatus. In a subsequent phase, cocaine exposure continued; however, on the unpaired side, separate group of rats had access to novel objects, cocaine injections, or saline with no objects. Pairings with novel objects or cocaine shifted a preference away from the cocaine-paired environment during drug-free and drug-challenge tests. Experiment 2 tested novelty's impact when cocaine exposure was discontinued. The identical procedures were used except drug exposure ceased on the cocaine-paired side during the second phase. Both groups expressed a preference for the cocaine compartment. This preference was maintained for rats that did not have novel objects; however, rats that experienced novelty spent similar amounts of time in both compartments during both tests. Overall, the conditioned rewarding effects of novelty competed with those of cocaine as evidenced by a change in choice behaviors motivated by drug reward.

Publication types

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

MeSH terms

  • Analysis of Variance
  • Animals
  • Behavior, Animal / drug effects
  • Cocaine / administration & dosage*
  • Conditioning, Operant / drug effects*
  • Conditioning, Operant / physiology*
  • Dopamine Uptake Inhibitors / administration & dosage*
  • Exploratory Behavior / physiology*
  • Male
  • Motor Activity / drug effects
  • Motor Activity / physiology
  • Rats
  • Rats, Sprague-Dawley
  • Reward*

Substances

  • Dopamine Uptake Inhibitors
  • Cocaine