Adenosine 2A receptor-dopamine D2 receptor (A2AR-D2R) heterodimer is located in the ventral striato-pallidal GABA neurons.335,336 A2AR-D2R heterodimer attracts attention in the field of Parkinson’s disease medication as ligands for A2AR can modulate dopamine signaling in Parkinson’s disease. This evidence concerns the gene DRD2 and Parkinson disease.