Contextual enhancement on binge-like overconsumption of palatable sugar in mice
Binge eating disorder is an eating disorder characterized by the excessive intake of food within a short period, often beyond physiological needs. Studies using animal models have shown that binge eating animals consume food in quantities that surpass physiological necessity, and that the neural mechanisms underlying this behavior overlap with those involved in habit formation. Habitual behaviors are thought to be automatic responses acquired through extended behavioral training and are dependent on the context in which they were learned. Therefore, this study hypothesized that binge eating has a context-dependent component. We investigated whether the excessive palatable sugar intake observed in an animal model of binge eating is triggered by an associated context as a learned behavior. To test this, mice were trained to develop binge-like sugar consumption in a specific context. During the test phase, we reduced the animals hedonic needs for sugar solution by providing a two-hour satiety period. Sugar solution was then presented in both the training context and a novel context (Experiment 1) or a negative context (Experiment 4). The results showed that in the training context, the mice continued to consume sugar solution at levels similar to those observed at the onset of the satiation. In contrast, this context-induced sugar consumption was not observed in the novel context (Experiment 2), while a follow-up experiment employing conditioned place preference demonstrated the existence of contextual learning itself (Experiment 3). These findings collectively suggest that, like habitual behaviors, binge eating is induced under in the context-dependent manner and insensitive to the consequence of the behavior.