Effects of the D1 receptor antagonist SCH 23390 (SCH, 0.1 mg/kg, SC) and the D3 receptor antagonist GR103691 (GR, 0.2 mg/kg, SC) on the changes in (A–C) acoustic startle and (B–D) prepulse inhibition (PPI) induced by the D1–D2 receptor agonist apomorphine (APO, 0.25 mg/kg, SC) in male Sprague-Dawley rats. Values represent mean ± SEM for each experimental group. N = 8–10/group. SAL, saline; VEH, vehicle; *, P<0.05; **, P<0.01; ***, P<0.001 for comparisons indicated by dotted lines. Curvy brackets are used to indicate main effects. For more details, see text.