Progestin-induced changes in play behaviour of the prepubertal rat.

The effects of neonatal exposure to medroxyprogesterone acetate on later play behaviour was studied. The experiments reported here indicate that animals of both sexes exposed to the hormone neonatally show lower levels of rough-and-tumble play in the prepubertal period. The effect is primarily one on play initiation: the organisation of play behaviour once initiated is not significantly affected, and the effect on play does not seem to be secondary to effects on some other behaviour. Several hypotheses are considered that might account for these findings.