Grant: Operating Grant

The brain chemical dopamine is best known for its role in motivation and motor control. More recently, however, animal studies have implicated dopamine also in pain relief. Studies that point at impaired dopamine systems in the brains of some patients with chronic pain suggest that a thorough understanding of the role of this chemical, its receptors and pathways is clinically relevant. No experimental study has yet investigated the effects of reduced dopamine availability in the brain on human pain perception. We therefore propose to decrease brain dopamine in healthy volunteers using acute dietary dopamine depletion to study the role of dopamine in pain sensitivity and the individual's capacity to modulate pain sensations. By combining thorough psychophysical studies with Positron Emission Tomography of the brain, we will also examine the localization of any pain increase due to reduced dopamine levels. Thereby, we will gain insight as to which dopaminergic pathways are involved in pain relief. We will assess certain character traits in all participants because we have preliminary data suggesting that certain traits make people less vulnerable to a pain-augmenting effect of reduced dopamine levels. All experiments will be performed in men and women. This is of crucial importance because the pain conditions for which impairment of dopamine systems has been shown are more often diagnosed in women. The proposed research is likely to yield important insights into the importance of dopamine for human pain processing and why some chronic pain syndromes occur more frequently in women than in men. This knowledge could potentially be used to devise new diagnostic and therapeutic option for affected patients.