Behavioral Economic Analysis of Binge Eating in Female Rats; Glucocorticoid Receptor Expression Level in the Central Amygdala after Intermittent Access to Palatable Food

Binge eating is characterized by eating a large amount of food within a short period of time with the feeling of loss of control. We applied the principles of behavioral economics, which separate consumption into unconstrained demand (Q0) and elasticity of demand (α) to study binge eating. We found that rats with intermittent access to palatable diet (INT) had increased Q0 and decreased α comparing to rats with ad-libitum chow (CHOW) or palatable diet (CHOC), which correlated with greater palatable food intake and consumption during self- administration. Within INT group, Q0 positively correlated with fixed ratio self-administration responses. Initial chow intake, initial body weight, and first-day palatable diet intake predicted higher α. Results show behavioral economic measures have predictive values in assessing compulsive eating.Drug dependence has been implicated with the change in glucocorticoid receptor (GR) levels in the central amygdala (CeA), where its elevation relates to negative affect upon abstinence, increasing likelihood of relapse through negative reinforcement. Here we accessed change in GR mRNA expression in rats after intermittent access to palatable diet. Results showed that female, but not male, INT rats had higher expression comparing controls; female INT rats had higher expression than male counterparts; and female INT rats with substantially high progressive-ratio response showed significantly higher expression comparing to controls, while other female INT rats did not. Results show sex and individual-level differences in the development of compulsive eating, suggesting differences in neuroadaptation in response to intermittent access diet schedule