Environmental cues, alcohol seeking, and consumption in baboons: Effects of response requirement and duration of alcohol abstinence

Background: Environmental stimuli (cues) that have been paired with alcohol drinking may evoke classically conditioned states that in turn influence alcohol consumption and relapse to heavy drinking. Animal models using chained schedules of alcohol reinforcement may be useful for examining such complex interactions. Methods: Alcohol drinking was established in 4 baboons. A sequence of lights and tones was presented during daily 3-hour sessions. First, cues were presented alone and no programmed contingencies were in effect. Second, cues were paired with 3 linked components consisting of different behavioral contingencies leading to and concluding with access to alcohol for self-administration in the last component (i.e., a chained schedule of alcohol reinforcement). Third, the effects of withholding alcohol access (i.e., forced abstinence) and increasing the number of lever responses required per drink were evaluated. Results: Cues paired with a chained schedule of alcohol reinforcement engendered behaviors that brought baboons into contact with alcohol-related cues and occasioned operant responding that facilitated access to alcohol (alcohol seeking) during components that preceded alcohol access. Increasing the response requirement for each drink decreased the number of drinks and volume of alcohol consumed, but did not alter alcohol seeking. On the first session after 14 days of alcohol abstinence, latency to complete the operant requirement that produced alcohol access was decreased while both alcohol self-administration and volume of alcohol consumed were increased. Conclusions: Alcohol self-administration and consumption were sensitive to increases in response requirement and duration of alcohol abstinence, while seeking was only enhanced by duration of alcohol abstinence. This animal model may be useful to further examine the interactions between environmental cues and behaviors associated with seeking and consumption of alcohol and to evaluate the efficacy of potential alcohol treatment drugs on these behaviors.