Effects of Haloperidol on Responding Maintained with Food and Sucrose-Water

Abstract

The “hedonic” value of reinforcers is mediated by dopamine. Accordingly, haloperidol diminishes the value of reinforcers, interfering with the emission of operant behaviors. Alternatively, interference with dopamine transmission leaves animals directed towards the consumption of food. Thus, reinforcers remain intact after the administration of haloperidol. We assessed these possibilities with two types of reinforcers, food-pellets and sucrose-water, delivered under multiple schedules of reinforcement. Lever presses maintained by food-pellets generally was higher than that maintained by sucrose-water. Haloperidol produced dose-related decreases in lever presses and obtained reinforcers. Differences in lever presses maintained by the two types of reinforcers were preserved across doses. Subcutaneous administrations of haloperidol were more potent in decreasing lever presses than intra-peritoneal administrations. Decreases in lever pressing were not necessarily accompanied by substantial reductions in obtained food-pellets and sucrose-water reinforcers; under the effects of haloperidol rats continued to produce a considerable number of both types of reinforcers.