Effect of drugs influencing central 5-hydroxytryptamine mechanisms on amantadine-induced stereotyped behaviour in the rat.

Pretreatment with L-tryptophan, a precursor of 5-HT, was found to decrease the intensity of stereotyped behaviour induced by amantadine, while methysergide, a 5-HT antagonist, was found to increase the intensity of amantadine-induced stereotypy. These results suggest that the intensity of amantadine-induced stereotypy depends on the balance between central dopamine and 5-HT systems and that the central 5-HT systems may have an opposing, tonic effect upon central dopamine systems involved in the mediation of stereotypy. In contrast to L-tryptophan, however, pretreatment with quipazine, a 5-HT agonist, and clomipramine, a selective 5-HT neuronal reuptake blocker, was found to potentiate the stereotyped behaviour induced by amantadine.