Effect of ergometrine on methamphetamine and apomorphine stereotypy in the guinea-pig.

Pretreatment with the DAi receptor antagonist ergometrine (10, 20 mg kg−1 i.p.) significantly potentiated methamphetamine stereotypy and facilitated the induction of biting, gnawing or licking behaviour by amantadine. However, ergometrine (5–20 mg kg−1) did not significantly influence the stereotyped behaviour induced by the DAe receptor agonist apomorphine. The results suggest that the DAi antagonist ergometrine is effective in modifying the behaviours induced by methamphetamine and amantadine, agents which through released DA simultaneously activate both DAe and DAi receptors, but fails to modify the stereotyped behaviour induced by apomorphine which specifically activates only DAe receptors. However, the possibility that ergometrine might have potentiated methamphetamine stereotypy and facilitated the induction of biting, gnawing or licking behaviour by amantadine through modulation of the activity of the central noradrenergic and 5-hydroxytryptaminergic systems, which are reported to influence DA-mediated behaviours, also needs to be considered.