Play behavior in rats pretreated with scopolamine: increased play solicitation by the non-injected partner.

Play behavior was assessed in juvenile rat pups following chronic administration of scopolamine (0.5 or 1.0 mg/kg, i.p.) to one partner in each dyad of rats. Scopolamine administration significantly reduced the number of pins and mean pin duration of both playmates in pairs where only one rat was injected with scopolamine (irrespective of dose). However, dorsal contacts were significantly increased in rats exposed to a play partner that had been injected with scopolamine, indicating an increase in play solicitation when the partner was rendered non-responsive with this drug. These effects were stable and consistent over the course of 15 days of repeated testing in the presence of scopolamine. In other words, normal animals did not extinguish play solicitation even after prolonged periods of non-reciprocity. Upon cessation of drug treatment, play behavior returned largely to normal in both animals. Overall locomotor activity levels were significantly reduced in pairs where one rat had been injected with scopolamine. Together, these data suggest that the effects of repeated scopolamine are acute in nature, and that disruption of normal play behavior following chronic scopolamine treatment does not produce long-term impairments in social play behavior beyond acute action of the drug.