Antagonism of apomorphine- and d-amphetamine-induced stereotyped behaviour by injection of low doses of haloperidol into the caudate nucleus and the nucleus accumbens

Abstract

The effects of intracerebral injections of the dopa-mine-antagonist haloperidol upon stereotyped behaviour, induced by peripheral administration of apomorphine and d-amphetamine in rats, were investigated. A system was used by which injections into the brain could be performed during the stereotyped behaviour without disturbing the animals. Administration of low doses of haloperidol (2.5 and 5 Μg) bilaterally either into the caudate nucleus or into the nucleus accumbens resulted in a dose-dependent antagonism of stereotyped behaviour. Whereas the effect of haloperidol upon stereotyped behaviour, induced by apomorphine, consisted mainly in a shortening of the duration of action, more abnormal behavioural patterns were seen, when haloperidol was administered to animals, who had received d-amphetamine. No clear differences were found between injections into the caudate nucleus and injections into the nucleus accumbens. Neither administration of the local anesthetic agent procaine into the caudate nucleus nor into the nucleus accumbens did significantly reduce apomorphine-induced stereotyped behaviour. The possible way in which haloperidol, following central administration, influences stereotyped behaviour is discussed.