Stimuli predicting high-calorie reward increase dopamine release and drive approach to food in the absence of homeostatic need.

Animals and humans are motivated to consume high-fat, high-calorie foods by cues predicting such foods. The neural mechanisms underlying this effect are not well understood.Objective: We tested the hypothesis that cues paired with a food reward, as compared to explicitly unpaired cues, increase rats' food-seeking behavior by potentiating dopamine release in the nucleus accumbens, and that this effect would be less evident under satiety.
Methods: We used a simple discriminative stimulus task and electrochemical recordings of dopamine release in freely moving rats.
Results: We found that both food-predictive cue and hunger increased conditioned approaches to the receptacle (food-seeking behavior indicated by movement to the food receptacle). In addition, we observed dopamine release when the food-predictive cue (but not the unpaired cue) was presented, independent of hunger or satiety. Finally, we found a positive correlation between dopamine release amplitude and the number of conditioned approaches to the food receptacle in the sated condition, but not in the hungry condition.Discussion: Our results suggest that dopamine could drive seeking behavior for calorie-dense food in absence of homeostatic need, a core aspect of binge eating disorders.