Effects of quipazine and methysergide on play in juvenile rats

Social play of juvenile rats was analyzed following administration of either the serotonin receptor agonist quipazine (1, 2.5, 5 and 10 mg/kg) or the antagonist methysergide at the same doses. Quipazine reduced pinning at all doses, while methysergide did so at only the highest two. An interaction study using the lowest doses of the agents used above, indicated that methysergide could reverse quipazine induced reductions of play. Thus, the quipazine effect was probably mediated through a serotonin receptor; however, the role of serotonin in play appears to be a general modulatory one rather than a specific influence on play.