Conditioned place preference in the male Wistar-Kyoto rat

The current set of experiments examined the role of trait anxiety, using the Wistar-Kyoto (WKY) rat, on cocaine- and morphine-induced conditioned place preference. Both four and six pairings of 10mg/kg cocaine during conditioning yielded no significant preference at acquisition, yet a preference at reinstatement was observed after a protracted period of abstinence. The three pairings of 10mg/kg morphine yielded no significant preference for either of the outer choice chambers at any time point, however an increasing preference for the neutral chamber in which no injection was given was observed as extinction continued. Taken together, the data collected from these experiments suggest a model that is driven primarily by the negatively reinforcing properties of drugs (the reduction in anxiety induced by the drug following an extended period of abstinence). This research adds to the literature investigating the use of this model in the context of drug addiction.