Role of opioidergic and noradrenergic systems in central parkinsonian pain – PAINPARK

Pain is one of the cardinal non-motor manifestation of Parkinson’s disease (PD) encompassing different subtypes including the so-called “Central parkinsonian pain”. Central pain relies on a dysfunction of painful stimulus processing directly related to PD pathophysiology. Mechanisms of pain in PD are complex but neurodegenerative process involving widespread pain system centers at cortical, brainstem, basal ganglia and spinal cord levels, may contribute to abnormal central nociceptive processing. A large body of evidence supports a role of complex interaction between the opioidergic and dopaminergic system as one of the mechanisms of pain in PD. In addition, in the general population, both the opioidergic and noradrenergic systems play a major role in pain processing, with known interaction between them. Therefore, it appears highly relevant to perform a PET-MRI study using 11C-Diprenorphin, a non specific partial opioid agonist tracer and 11C-Yohimbine, an a2 adrenergic receptors antagonist tracer, in PD patients with and without central pain.