DRD3 and Parkinson disease: In the same direction, using a pharmacologic approach, we have found that systemic antagonism of DRD3 attenuates microglial activation and neuronal loss of the nigrostriatal pathway in two different animal models of PD, including those models of parkinsonism induced by chronic administration of MPTP or by the stereotaxic injection of 6-hydroxydopamine [25, 31].