PROLACTIN STIMULATION OF MATERNAL-BEHAVIOR IN FEMALE RATS

Inexperienced, hypophysectomized female rats treated with steroids [estradiol, progesterone] were used in experiments to investigate the roles of the pituitary gland and prolactin in the expression of maternal behavior. Administration of ovine prolactin or treatment with ectopic pituitary grafts, which release prolactin into the circulation, stimulated maternal care in these females toward rat young. Steroid treatment alone, while stimulating maternal behavior in rats with intact pituitary glands, did not facilitate maternal responsiveness in hypophysectomized females. A stimulatory behavioral role for pituitary prolactin in the establishment of maternal care was indicated. Exposure to prolactin during pregnacy evidently helps to stimulate the immediate onset of maternal behavior at parturition. [Prolactin is thought to exert it''s behavioral effects via CNS feedback.].