Seeking Behavior, Place Conditioning, and Resistance to Conditioned Suppression of Feeding in Rats Intermittently Exposed to Palatable Food

Binge eating disorder is characterized by excessive consumption of highly palatable food within short periods of time accompanied by loss of control over eating. Extensive evidence provides support for the consideration of binge eating disorder as an addiction-like disorder. In this study, we wanted to determine whether rats undergoing an operant binge-like eating procedure could develop maladaptive forms of conditioned feeding behaviors. For this purpose, we trained male rats to self-administer either a sugary, highly palatable diet (Palatable rats) or a chow diet (Chow rats) for 1 hour a day. Following escalation and stabilization of palatable food intake, we tested Chow and Palatable rats in i) a conditioned place preference test, ii) a second-order schedule of reinforcement, and iii) a cue-induced suppression of feeding test. In the conditioned place preference task, Palatable rats spent significantly more time in the compartment that was previously paired with the palatable food, compared to Chow controls. Furthermore, in the second order schedule of reinforcement task, Palatable rats exhibited active lever responding 4- to 6-fold higher than Chow control rats. Finally, in the cue-induced suppression of feeding test, while Chow control subjects reduced responding by 32% in the presence of the conditioned punishment, Palatable rats persevered in responding despite the aversive cue. These results further characterize this animal model of binge-like eating and provide additional evidence for the addictive properties of highly palatable food.