Effect of haloperidol and pimozide on acetylcholine output from the cerebral cortex in rats and guinea pigs.

The effect of haloperidol, pimozide and amphetamine on acetylcholine (ACh) output from the cerebral cortex was investigated in unanaesthetized, freely moving and urethane-anaesthetized rats and guinea pigs. Haloperidol (1 mg/kg i.p.) decreased ACh output only in the anaesthetized rats and increased it only in unanaesthetized guinea pigs. Pimozide (1 mg/kg i.p.) stimulated ACh output in unanaesthetized rats and guinea pigs and anaesthetized guinea pigs, but not in anaesthetized rats. Amphetamine (1 mg/kg i.p.) in all cases, stimulated ACh output. In rats with a septal lesion, the effect of amphetamine on ACh output was suppressed but that of pimozide was still present.