Effects of neurotensin receptor antagonists on the firing rate of rat ventral pallidum neurons

Using anaesthetized adult rats, we compared the effects of i.v. injections of neurotensin receptor antagonists (SR48692 and SRI42948), haloperidol and clozapine on neuronal firing rate in the two ventral pallidal areas. SR48692 (0.5, I and 2 mg/kg, i.v.) induced a dose-dependent inhibition of firing rate in two thirds of neurons in the ventromedial part without any effect in the ventrolateral part. These effects are in keeping with the preferential neurotensin immunoreactivity distribution reported in the ventral pallidum. The classical antipsychotic drug haloperidol (0.5 mg/kg, i.v.) induced ah inhibition of neuronal firing rate in both ventral pallidal areas whereas the atypical antipsychotic drug clozapine (20mg/kg, i.v.), like the neurotensin receptor antagonist SR48692, inhibited cell firing only in the ventromedial part.