| Abstract: | Rat pituitary tumors were induced by the monthly injection of high doses of estradiol valerate. Of 12 animals which received the estrogen, 10 developed tumors. From these 10 tumors, 4 cell lines were successfully established and they have been maintained in culture for over 18 months. Several clones have been isolated from these established cell lines. Three of the 4 cell lines produce tumors in females considerably faster than in males or castrated females. Tumor-bearing animals have significantly increased amounts of rat growth hormone and prolactin in their serum. The 4 established cell lines, as well as clones derived from them, and tumors obtained in situ by injection of these cells growing in culture or successive transplants have shown the presence of an estrogen-binding protein of high affinity and low capacity. This estrogen-binding protein is similar to that described in other target organs (uterus, mammary glands, etc). These cell lines will be used to study the mechanism of action of estrogen in target cells as well as the synthesis and secretion of pituitary hormones. |
