GLP1R and obesity due to melanocortin 4 receptor deficiency: In sum, we only observed uptake in the brain of 68Ga-NODAGA-exendin-4 in the pituitary area of subjects with obesity and it is becoming more likely that (part) of the mechanism of actions of GLP-1 receptor agonists and PET tracers on brain functions might be due to (slow) uptake by tanycytes, located in the median eminence/basal hypothalamus.