Risperidone regulates Dopamine D2-like receptors expression in rat brain in a time-dependent manner

Abstract

Background and Objectives: Antipsychotics can elicit dopamine super- sensitivity by up-regulation of D2-like receptors (DRD2, DRD3, and DRD4) expression. Nevertheless, the expression profile of dopamine D2-like receptors in different brain re- gions and peripheral blood mononuclear cells (PBMCs), and changes following risperi- done administration were still unclear. In this study, we would investigate the expression of D2-like receptors mRNA in different brain regions and the peripheral blood mononu- clear cells (PBMCs) in rats after 2, 6 weeks risperidone administration. Methods: The experimental rats were given risperidone (0.25mg/kg/day, i.p.), and the control rats were given 0.9% NaCl. The rats were sacrificed at 0 week, 2 weeks and 6 weeks after the drug administration. Expression of the dopamine D2-like receptors was quanti- fied by Real-time PCR method. Results : Dopamine D2-like receptors expressed in all the examined regions of rat brain. Their expression significantly increased 2weeks after risperidone administration in differ- ent brain regions. However, the changed expression of DRD2 and DRD3 turned back to the basal level 6weeks later, while the increased DRD4 expression remained in left pari- etal cortex. Meanwhile, DRD2 and DRD3 but not DRD4 expressed in PBMCs, however, the risperidone could not affect their expression. Conclusions: The risperidone could change the dopamine D2-like receptors expression in a time-dependent manner in different brain regions, which might guide the clinical use in the near future