Increment in the consummatory response induced by reward delay: An animal model of binge-like eating episodes

Abstract

The omission of an expected palatable reinforcer produces an aversive emotional state, called frustration, that could function as an important factor in the etiology and maintenance of the binge-eating disorder. A series of experiments carried out in adult male Wistar rats are presented, in which the consummatory response of sugary drinks was evaluated after events of frustration due to reward delay. The animals were trained in a consummatory behavior acquisition phase, in which they had access to different concentrations of sucrose solutions. In the test phase, a control group received the reinforcer normally, while an experimental group received it after a delay. A significant increase in the consummatory behavior of a 32 % sucrose was found in the group that was exposed to a 2-min delay before re-introducing the reinforcer (Experiment 1). The increment found in the consummatory response was dependent on the aversive state of frustration. This could be concluded because, in a less frustrating condition, the animals did not exhibit the phenomenon (Experiment 2), and a more frustrating one produced an increment of the effect (Experiment 3). This result was also observed using a direct measure of consumption -kilocalorie intake- during several events of reinforcement delay (Experiment 4).