THE ROLE OF LACTOGENIC HORMONES IN MATERNAL-BEHAVIOR IN FEMALE RATS

Most mammals display an immediate onset of maternal care towards their offspring at parturition. In contrast, inexperienced, nulliparous fem ales are often slow responders and show less intensity in their matern al responses. The transition from a slow responder in non-parous femal es to a rapid response at parturition is facilitated by the endocrine state of pregnancy. The present report reviews recent evidence from my laboratory demonstrating a role for prolactin in the stimulation of m aternal behavior in the rat and presents new findings suggesting that the conceptus, through its secretion of placental lactogens, helps pri me the maternal brain (one site being the medial preoptic area) to res pond maternally at parturition.