In has been reported obese individuals have fewer striatal dopamine type 2 receptors (DRD2) compared to normal weight individuals congruent with diet induced obese rodent models and similar to models of addiction. Lower DRD2 levels are associated with addiction and a decreased sense of pleasure. Excessive weight gain also contributes to the onset of impaired insulin signaling (insulin resistance). In the brain insulin regulates monoamines and has trophic effects. We propose that the previous reports of low DRD2 in individuals with obesity will be associated with the degree of insulin resistance. Using PET imaging, we aim to determine DRD2 binding potential (BP) in the striatum and hypothesize these measurements will be associated with insulin resistance and potentially other neuroendocrine hormone levels. Obese participants will be compared to lean, sex and age similar participants. We also aim to determine the effect of caloric restriction on DRD2 BP in obese subjects. We hypothesize the caloric restriction will improve insulin resistance and that changes in DRD2 binding will be associated with changes in insulin signaling.
Obese individuals have fewer striatal dopamine type 2 receptors (DRD2) than normal weight individuals. Lower DRD2 levels are associated with addiction and a decreased sense of pleasure.Obesity is also associated with insulin resistance (poor insulin action).We propose that insulin resistance and low DRD2 are associated. Using PET imaging,we aim to determine DRD2 binding potential (BP) in the brain is associated with insulin resistance and neuroendocrine hormone levels. Obese participants will be compared to lean, gender and age similar participants. We also aim to determine the effect of caloric restriction on DRD2 BP in obese subjects