[Comparative evaluation of the effect of haloperidol and clozapine on rotational movements induced by caudate nucleus stimulation in cats].

Chronic experiments on cats were carried out to study the effect of haloperidol and clozapine on the pattern of contralateral rotations produced by electric stimulation of the caudate nucleus. Haloperidol (0.125 mg/kg) facilitated the appearance of the reactions during stimulation of the lateral parts of the nucleus while clozapine selectively decreased the thresholds of the "manage" movements in the course of stimulating but the medial zones of the structure. Unlike haloperidol, clozapine (2.5 mg/kg) eliminated the forced reactions of the tonic type originating from the lateral parts of the caudate nucleus. Haloperidol (0.125 mg/kg) suppressed the stereotyped behavior caused by DOPA (100 mg/kg) and apomorphine (5 mg/kg). Clozapine (2.5 mg/kg) reduced the stereotyped behavior produced by amphetamine (2 mg/kg) but did not exert any action on apomorphine effects. It is suggested that clozapine suppression of the tonic effects originating from the lateral parts of the caudate nucleus is responsible for poor intensity of extrapyramidal disorders seen in clinical application of this agent.