Operant self-administration of chocolate in rats: An addiction-like behavior

This chapter provides a detailed description of an operant procedure of self-administration of a chocolateflavored beverage in rats. Specifically, rats are trained to lever-respond--on a Fixed Ratio 10 schedule of reinforcement--for a 5-s presentation of the chocolate-flavored beverage in daily sessions. Rats quickly learn to lever-respond for the chocolate-flavored beverage and steadily maintain high levels of leverresponding (approximately 2000 lever-responses in 60-min sessions), self-administering large amounts of the chocolate-flavored beverage (60-70 ml/kg/session). This procedure can also be successfully applied to studies using several other schedules, including Progressive Ratio, extinction responding, and cueinduced reinstatement of seeking behavior. Usefulness of this procedure spans from investigations on the neurobiological bases of food-related, addiction-like behaviors to screening compounds potentially effective in overeating disorders