Social play in juvenile rats during scopolamine withdrawal.

Scopolamine induced blockade of play fighting in juvenile rats and the rapid induction of behavioral tolerance to an initially effective dosage suggested a rebound in social play following chronic scopolamine exposure. Juvenile rats received daily intraperitoneal scopolamine or saline injections for one week. Play soliciting and play fighting behavior were then measured at 24 and 168 hr after drug withdrawal. Scopolamine treated juveniles engaged in markedly greater play soliciting and play fighting behavior than did controls. Drug-induced increase in muscarinic receptors and supersensitivity to endogenous acetylcholine following scopolamine withdrawal is suggested as the basis for observed differences in social play.