Supplementary data for article: Central insulin modulates dopamine signaling in the human striatum

Objective: Activity in the dopaminergic pathways of the brain is highly sensitive to body weight and metabolic states. Animal studies show that dopamine neurons are important targets for the metabolic hormone insulin with abolished effects in the insulin resistant state, leading to increases in body weight and food intake. In humans, the influence of central acting insulin on dopamine and effects of their interplay are still elusive.

Research Design and Methods: We investigated whether central administered insulin influences dopaminergic activity in striatal regions and whole-brain neural activity. Using a PET/MRI hybrid scanner, we simultaneously performed [11C]-raclopride-PET and resting state fMRI in 10 healthy normal weight men after application of intranasal insulin or placebo on two separate days in a randomized, placebo-controlled, blinded, crossover trial.

Results: In response to central insulin compared to placebo administration, we observed greater [11C]-raclopride bindi...