Effects of pallidal infusion of dopamine receptor antagonists on PPI deficits.

Different doses of the D1-like receptor antagonist [SCH23390; 0 µg (vehicle), 0.5 µg or 2 µg per site] or the D2-like receptor antagonist [raclopride; 0 µg (vehicle alone), 0.5 µg or 2 µg per site] were administered to both hemispheres of the globus pallidus of EGF and control rats. (A) Cannula placement was confirmed in fixed brains, and four out of 69 rats were excluded from the final data analysis due to incorrect cannula placement. Rats receiving SCH23390 (B) or raclopride (C) were subjected to PPI test with 75-, 80- and 85-dB prepulse stimuli combined with a 120-dB startle tone. Pulse-alone startle responses to a 120-dB tone were measured in arbitrary units and are shown in the inset. Bars indicate mean ± SEM (N = 8–9 for each group). Data of rats receiving vehicle alone (control) were shared in (B) and (C). *P<0.05, **P<0.01, compared with vehicle-infused controls; +P<0.05, ++P<0.01, compared with vehicle-infused EGF rats by Fisher's LSD.