DRD2 and Parkinson disease: However, in the dorsal striatum, a significant decrease in the positive cell number of D2R was observed in the PD group when compared with levels observed in the control group (419.50 ± 9.68 vs 236.00 ± 36.75, P < 0.001, F = 93.253), while a similar, significant increase was observed in PE mice when compared with levels observed in the PD group (284.75 ± 18.69 vs 236.00 ± 36.75, P < 0.05, F = 5.591) (Fig. 12).