Prolactin-steroid influences on the thermal basis for mother-young contact in Norway rats.

Norway rat dams have a chronic elevation in core temperature throughout the first 2 wk postpartum, a situation that makes them vulnerable to a further, acute rise in body temperature during contact with their young. Prolactin appears to contribute to the chronic elevation of maternal temperature, probably by stimulating the secretion of progesterone, which then elevates the maternal thermal set point.