Locomotor response to novelty predicts a rat's propensity to self-administer nicotine

Abstract

Rationale: A positive correlation between responding to novelty and propensity to subsequently self-administer a drug has been reported for opioids and psychomotor stimulants but remains to be investigated for nicotine.

Objective: The possibility that locomotor responding to novelty can predict a rat's propensity to self-administer nicotine was therefore assessed.

Methods: Rats' locomotor response to a novel environment was assessed, and animals were subsequently tested for their self-administration of nicotine.

Results: Significant positive correlations were obtained between responding to novelty and acquisition of nicotine self-administration over 12 days of testing under fixed-ratio schedules as well as subsequent responding for the drug under a progressive-ratio (PR) schedule of reinforcement. When designated as high (HR) or low (LR) responders based on whether their locomotor responses on the novelty screen were above or below the median activity level of the subject sample, HR animals, compared with LR rats, acquired nicotine self-administration more readily and worked more to obtain the drug when tested under the PR schedule.

Conclusion: These findings are consistent with those obtained with other drugs and suggest that locomotor responding to a novel environment can be used to predict a rat's propensity to self-administer nicotine.