ADORA2A and Parkinson disease: Many adenosine A2a receptor antagonists have shown various efficacies in preclinical studies, such as haloperidol-treated rodents, 6-hydroxydopamine (6-OHDA)-lesioned rats, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated primates, and clinical trials in PD [27].