Synergism between Prolactin and Ovarian Hormones on DNA Synthesis in Rat Mammary Gland 1

Summary

Autoradiography with [³H] thy-midine has been used to measure the rate of DNA synthesis in the mammary epithelium of hypophysectomized-ovariectomized rats under the influence of estradiol, progesterone, and prolactin. Controls and animals treated with estradiol did not increase [³H]thymidine incorporation, while progesterone alone had a slight stimulatory effect. Prolactin alone stimulated some [³H]thymidine uptake in ductal and alveolar epithelium, but when combined with either estradiol or progesterone synergistic effects were observed. Estradiol with prolactin stimulated incorporation primarily in the ductal epithelium, whereas progesterone with prolactin stimulated both ductal and alveolar epithelium.