Impact of nicotine withdrawal on novelty reward and related behaviors.

The authors tested the decreased reward function hypothesis of nicotine withdrawal using a novel-object place conditioning task. A conditioned place preference was evident in controls and in rats that had experienced 4 nicotine withdrawal days, but not in rats that had experienced 1-3 withdrawal days. This implies that the rewarding properties of interacting with novel objects were not readily associated with the environment in which they were paired. Follow-up experiments eliminated other explanations based on withdrawal-induced failures to process object or environment information. Also, expression of conditioning was not affected, indicating that withdrawal likely altered acquisition. Further investigation into the neurochemical and behavioral changes that accompany nicotine withdrawal will lead to a better understanding of the withdrawal syndrome.