Dopaminergic antagonism of L-5-hydroxytryptophan-induced myoclonic jumping behavior.

We studied the effect of dopamine agonists (levodopa, apomorphine, lergotrile, and M-7 [2(dimethylamino)5,6-dihydroxytetralin] on myoclonic jumping behavior in young male guniea pigs. All these agents had a significant antagonistic effect on the frequency of this serotonin-mediated behavior. The duration of the antagonism corresponded in all cases to the duration of stereotyped chewing behavior induced by these agents alone. The dopamine antagonist haloperidol potentiated jumping behavior. Therefore myoclonic jumping behavior is influenced by dopaminergic mechanisms, and this behavior may be the result of interaction between dopaminergic and serotonergic activity. The role of dopaminergic mechanisms in human myoclonic disorders needs further clarification.