Wistar Kyoto rats exhibit reduced sucrose pellet reinforcement behavior and intravenous nicotine self-administration.

A phenotype of heightened anxiety-like behavior is hypothesized to be associated with altered reinforcement behavior. To test this hypothesis, we studied patterns of sucrose pellet intake and intravenous nicotine self-administration in animals that exhibit anxiety-like behavior at baseline, Wistar Kyoto (WKY) rats, as compared to normal controls (Wistar rats). WKY rats exhibited significantly reduced sucrose pellet self-administration behavior as assessed by both fixed and progressive ratio schedules of reinforcement and exhibited significantly reduced self-administration of intravenous nicotine. On the basis of previously published findings, we hypothesize that altered mesolimbic dopamine responses, as well as heightened HPA axis functioning, may account for reduced nicotine self-administration and sucrose pellet reinforcement responding in WKY rats. These studies highlight the role of heightened anxiety-like behavior, resulting from the genetic background of the animal, in altering behavioral responses to reinforcing stimuli.