Differential effects of 5-hydroxytryptaminergic antagonists upon apomorphine- and lergotrile-induced hypothermia and stereotyped behaviour in rats

Abstract

Abstract The dopaminergic stimulants apomorphine and lergotrile both evoked hypothermia and stereotyped behaviour in rats. These drug effects were sensitive to antagonism by haloperidol, a dopaminergic receptor blocker. In rats pretreated with 5-hydroxytryptaminergic receptor blockers, cinanserin reduced apomorphine-induced hypothermia but cyproheptadine did not. Both cinanserin and cyproheptadine significantly potentiated lergotrile-induced hypothermia. Similarly, the stereotypic effects of apomorphine were partly reduced by cyproheptadine, although higher doses of cyproheptadine did potentiate lergotrile-induced stereotyped behaviour. These findings of different influences of 5-HT antagonists upon the effects of apomorphine and lergotrile indicate that these two dopaminergic stimulants may not work in identical manner to produce outwardly similar drug effects.