OBJECTIVETo explore the mechanism underlying the therapeutic effect of Bushen Huoxue Decoction (BHD), a traditional Chinese medicinal preparation, on dopamine D2 receptor (DRD2) in the brain of rat models of Parkinson's disease (PD).

METHODSA total of 120 SD rats were randomized into normal control group, saline model group and BHD-treated group. In the latter two groups, PD rat models were established by direct injection of 6-OHDA to destruct the substantia nigra compact part (SNC) with corresponding treatments. The behavioral changes of the rats were observed. Radioimmunoassay was employed to determine the changes in the equilibrium dissociation constant (Kd) and maximal binding capacity (B(max)) of DRD2, and immunohistochemistry was used to observe the number of the DRD2-positive cells in the brain of the rats.

RESULTSBHD can markedly improve the behavioral abnormalities of PD model rats. Compared with those in the saline model group, the B(max) of DRD2 in the damaged hemisphere increased while the Kd of BHD decreased significantly after BHD treatment (P<0.01). The number of DRD2-positive cells in BHD-treated group was significantly higher than that in the model group (80.9∓13.59 vs 11.15∓6.78, P<0.01), but showed no significant difference from that in the normal control group (P>0.05).

CONCLUSIONBHD can improve the behavioral abnormalities and increase the cerebral expression and affinity of DRD2 in PD rat models.