The importance of vaginal-cervical stimulation for maternal behaviour in the rat.

Non-parturient female rats were primed with oestrogen and given 5 minutes of vaginal-cervical stimulation before foster pups were introduced to them. Virgin and multiparous Wistar rats were used and half the females were ovariectomised. Half of each group was given vaginal-cervical stimulation and the other half was handled for the same time period. An animal was designated "maternal" if it showed all components of maternal behaviour (i.e., retrieving, licking, and crouching). A group of normal, parturient females was observed to compare their normal maternal behaviour with that of experimental animals. Significantly more intact multiparous females showed immediate maternal behaviour after stimulation (75%) than after handling (30%, p less than 0.04). However, virgin females showed no maternal behaviour in response to vaginal-cervical stimulation. This study shows that sensory input from the vagina plays an important role in the immediate induction of maternal behaviour, but this effect is synergistic with that of hormones and experience.