Sb. Schwarzkopf et al., EFFECTS OF HALOPERIDOL AND SCH 23390 ON ACOUSTIC STARTLE AND PREPULSEINHIBITION UNDER BASAL AND STIMULATED CONDITIONS, Progress in neuro-psychopharmacology & biological psychiatry, 17(6), 1993, pp. 1023-1036
1. Adult Sprague-Dawley rats underwent startle testing for assessment
of baseline startle amplitude and prepulse inhibition (PPI) of the sta
rtle reflex. 2. Animals were tested after administration of either: sa
line, a selective D1 dopamine (DA) receptor antagonist, a relatively s
elective D2 DA antagonist, or combined low dose D1 and D2 antagonists.
3. Changes due to antagonists were assessed with and without administ
ration of the D1/D2 agonist apomorphine. 4. Testing without apomorphin
e stimulation showed that both D1 and D2 antagonists reduce baseline s
tartle and enhance PPI. Further, the two antagonists exhibited a syner
gistic 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 D
1 antagonist reduced the apomorphine effect. However, the D1 antagonis
t potentiated the effect of the D2 antagonist.