Effects of haloperidol and SCH 23390 on acoustic startle and prepulse inhibition under basal and stimulated conditions.
1. Adult Sprague-Dawley rats underwent startle testing for assessment of baseline startle amplitude and prepulse inhibition (PPI) of the startle reflex. 2. Animals were tested after administration of either: saline, a selective D1 dopamine (DA) receptor antagonist, a relatively selective D2 DA antagonist, or combined low dose D1 and D2 antagonists. 3. Changes due to antagonists were assessed with and without administration of the D1/D2 agonist apomorphine. 4. Testing without apomorphine stimulation showed that both D1 and D2 antagonists reduce baseline startle and enhance PPI. Further, the two antagonists exhibited a synergistic interaction. 5. Testing with apomorphine showed that D1 and D2 antagonists reduce apomorphine-induced startle enhancement. Again, the two exhibited a synergistic interaction. 6. For PPI, the D2 but not D1 antagonist reduced the apomorphine effect. However, the D1 antagonist potentiated the effect of the D2 antagonist.
Schwarzkopf
S B
SB
Department of Psychology, University of Rochester, N.Y.
Bruno
J P
JP
Mitra
T
T
D000161:Acoustic Stimulation; D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D001552:Benzazepines / Q000494:pharmacology*; D065127:Dopamine D2 Receptor Antagonists; D004357:Drug Synergism; D006220:Haloperidol / Q000494:pharmacology*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D017447:Receptors, Dopamine D1 / Q000037:antagonists & inhibitors; D013216:Reflex, Startle / Q000187:drug effects*
D001552:Benzazepines; D065127:Dopamine D2 Receptor Antagonists; D017447:Receptors, Dopamine D1; D006220:Haloperidol; D001058:Apomorphine