Figure 4.

Effects of repeated administration of phencyclidine (PCP) on dopamine and adenosine 3’,5’-cyclic monophosphate activated phosphoprotein of 32 kDa (DARPP-32) phosphorylation in D32 ^F/F D1RCre ⁺ and D32 ^F/F D2RCre ⁺ mice. (A) D32 ^F/F D1RCre ⁺ and (B) D32 ^F/F D2RCre ⁺ conditional knockout mice and (A) D1RCre and (B) D2RCre control mice were treated for 8 days (one injection/day) with vehicle or PCP (3mg/kg) and killed by decapitation 30min after the last injection. DARPP-32 phosphorylation on Thr34 was determined by Western blotting as described in Methods. Upper panels are representative Western blots showing phosphorylated DARPP-32 (top) and total DARPP-32 (bottom). Note the reduction in total DARPP-32 produced by genetic inactivation in (A) D1R- or (B) D2R-expressing MSNs. The increase in phosphorylated DARPP-32 induced by PCP is abolished in (A) D32 ^F/F D1RCre ⁺ mice, but still present in (B) D32 ^F/F D2RCre ⁺ mice. Lower panels are mean ± standard error of the mean (n = 5–8/group) of data expressed as percent of (A) D1RCre or (B) D2RCre mice injected with vehicle. *p < 0.05 and **p < 0.01 vs. vehicle-treated mice, same genotype; ##p < 0.01 vs. vehicle-treated mice of respective control genotype (two-way ANOVA, followed by Fisher’s post hoc comparison).