Responsiveness of 5αR1-deficient mice to the effects of D1 and D2 receptor agonists on startle reflex and prepulse inhibition (PPI). Data are shown as means ± SEM. ^P<0.05, ^^^P<0.001 in comparison with wildtype (WT) mice (Main effect of genotype). ***P<0.001 vs vehicle (VEH)-treated WT mice (genotype x treatment interaction). #,P<0.05, ###P<0.001 vs WT mice treated with dopaminergic agonists (genotype x treatment interaction); ooo,P<0.001 vs KO mice treated with VEH (genotype x treatment interaction). The number of mice in each group is indicated. Abbreviations: HZ, 5αR1 heterozygous; KO, 5αR1 knockout; SKF, SKF 82958 (0.3 mg/kg, IP); QUIN, QUIN (0.5 mg/kg, IP).