Molecular Imaging of the Cannabinoid System in Idiopathic Parkinson's Disease

The endocannabinoid system is a modulator of neurotransmitter release and is involved in several physiological functions. Hence, it has been increasingly studied as a potential pharmacologic target of Parkinson's disease. Several preclinical and clinical studies evidenced a substantial rearrangement of the endocannabinoid system in the basal ganglia circuit following dopamine depletion. The endocannabinoid system has been additionally implicated in the regulation of neuroinflammation and neuroprotection through the activation of CB2 receptors, suggesting a potential target for disease modifying therapies in Parkinson's disease. In this chapter, current pharmacological and physiological knowledge on the role of the endocannabinoid system will be reviewed, focusing on preclinical studies animal models and clinical studies in patients with idiopathic Parkinson's disease. The main strategies for imaging the brain cannabinoid system will be summarized to finally focus on in vivo imaging of patients with Parkinson's disease.