μ-opioid receptor system mediates reward processing in humans

Description: The endogenous μ-opioid receptor (MOR) system is involved in hedonic and motivational processing. We tested directly whether individual differences in MOR are associated with reward responses to food pictures in humans. We scanned 33 non-obese individuals with positron emission tomography (PET) and MOR-specific radioligand [11C]carfentanil. The subjects also underwent a functional magnetic resonance imaging (fMRI) experiment where they viewed pictures of appetizing versus bland foods to trigger reward responses. MOR availability was measured in key components of the reward and emotion circuits and used to predict BOLD-fMRI responses to foods. Viewing palatable versus foods activated regions involved in homeostatic and reward processing, such as amygdala, ventral striatum and hypothalamus. MOR availability in the reward and emotion circuit was negatively associated with the visual reward responses in fMRI. Variation in MOR availability may explain why some people feel a strong urge to eat when encountering food cues, and increase risk for weight gain and obesity.

Related article: http://doi.org/10.1038/s41467-018-03848-y