Failure of antiserotonergic agents to modify levallorphan-induced stereotypy in rats

The possibilty that the stereotypic behaviour induced by levallorphan, a narcotic antagonist, might be influenced by a serotonergic system was examined. Two antiserotonergic agents, methysergide and parachlorophenylalanine, failed to modify such stereotypy implying that serotonin is not involved. It is suggested that dopamine might be the principle mediator of this behaviour.