Regional μ-opioid receptor binding in insular cortex is decreased in bulimia nervosa and correlates inversely with fasting behavior

The endogenous opioid system of the brain has been implicated in feeding behavior. Abnormal repeated activation of this system may constitute a neural substrate for the compulsive eating behavior observed in bulimia nervosa. This study examined the binding potential of the brain μ-opioid receptor (μ-OR) in bulimia nervosa. Methods: Eight women with bulimia nervosa and 8 female controls underwent brain MRI followed by ¹¹C-carfentanil PET. Voxel-based methods were used to assess group differences in μ-OR binding between controls and bulimic subjects and to correlate μ-OR binding with the frequency of recent self-reported abnormal eating behaviors in bulimic subjects. Results: μ-OR binding in the left insular cortex was less in bulimic subjects than in controls and correlated negatively with recent fasting behavior. Conclusion: Changes in μ-OR binding in the insula may be important in the pathogenesis or maintenance of the self-perpetuating behavioral cycle of bulimic subjects because the insula is the primary gustatory cortex and has repeatedly been implicated in the processing of the reward value of food.