DRD2 and Parkinson disease: The reduction in D2R expression from this study is similar to Farkas’s study where the binding of [3H]raclopride, which has 11.25 folds preferential binding to D2R than D3R, in PD postmortem putamen is ~ 8% of the control group (PD 3.73 ± 0.07, control 47.97 ± 10.00 fmol/g).11