Co-administration of dopamine precursor L-DOPA (L-3,4-dihydroxyphenylalanine) and dopamine receptor agonists could improve mobility in Parkinson’s disease.141 It has been shown that adenosine antagonists such as caffeine could enhance dopamine agonist action in Parkinson’s disease treatment.337 A2AR activation can suppress D2R-mediated Gi/o signaling.335 Stimulating A2AR with adenosine A2AR agonist in the nucleus accumbens produces behavioural effects similar to local dopamine depletion.338 Thus, the action of A2AR modulators should be considered in the drug design for Parkinson’s disease. Here, DRD2 is linked to Parkinson disease.