Rapid Changes in D1 and D2 Dopamine Receptor Binding in Striatal Subregions after a Single Dose of Phencyclidine

OBJECTIVE: In humans, a single exposure to phencyclidine (PCP) can induce a schizophrenia-like psychosis which can persist for up to two weeks. In rats, an acute dose of PCP increases dopaminergic activity and causes changes in dopamine related behaviours some of which are sexually dimorphic. To better understand the effects of PCP on dopamine receptor adaptations in the short term we examined dopamine D1-like receptors (D1R) and D2-like receptors (D2R) in the mesolimbic and nigrostriatal dopamine pathways, 4 hours after exposure to PCP in female rats. METHODS: Animals received a single dose of 40 mg/kg PCP and were sacrificed 4 hours later. In vitro autoradiography was carried out using [(3)H] SCH 23390 and [(3)H] raclopride that target D1R and D2R respectively, in cryostat brain sections. RESULTS: Two way analysis of variance (ANOVA), revealed an overall effect of PCP treatment (F [1,63]=9.065; p=0.004) on D1R binding with an 18% decrease (p<0.01) in binding in the medial caudate putamen. PCP treatment also had an overall effect on D2R binding (F [1,47]=5.450; p=0.024) and a trend for an increase in D2R binding across all the brain regions examined. CONCLUSION: These results suggest opposing D1R and D2R adaptations in striatal subregions of female rats following acute exposure to PCP that may occur through indirect mechanisms.