抄録
Pituitary homografts were placed in the spleen of the female Sprague Dawley rats for observing release of prolactin after subsequent hypophysectomy in the early course of gestation and lactation.
Maintaining Pregnancy: Grafting a single pituitary gland under the caspule of the spleen was performed on 3 to 6-day of pregnancy in 7 rats. Hypophysectomy through auricular route was done on 8 or 9-day of pregnancy. It is well known that hypophysectomy before 11th clay of pregnancy of the rat usually results in resorbtion or expulsion of the fetuses. In the present experiment the pregnancy was maintained in 4 out of 7 hypophysectomized-grafted rats. The growth of fetuses was almost in normal range. There were a lot of corpora lutea in the ovaries, and mammary glands developed well. Pregnancy could be maintained owing to the function of the grafted pituitary from the day of hypophysectomy to the clay of complete formation of the placena. Splenic pituitary homograft might release sufficient prolactin for stimulation of the corpora lutea to secrete progesterone which was necessary for maintaining pregnancy.
Maintaining the Lactation: Transplantation was performed in late stage of pregnancy in 19 rats and hypophysectomy was done on 3 to 9-day post partum. After hypophysectomy 12 out of 19 rats were treated with 3 times a day injections of ACTH (total dose: 3.0 i.u./day) and oxytocine (total dose: 3.0 i.u./ day). Hypophysectomy in the rat post par tum resulted in prompt cessation of lactation. In the present experiment, splenic pituitary graft could not cover the lactation in hypophysectomized rat post par tum and all the youngs died of starvation. Lactation was induced by renal pituitary graft in tats according to Rothchild. Prolactin release out of the splenic graft flew through the liver via the portal vein and must have lost some activity. It is concluded that prolactin release from the splenic pituitary homograft, which was not under control of hypothalamus, was adequate in maintaining pregnancy but not in lactation of hypophysectomized rats, due to the fact that lactogenic function of the prolactin was considered to be inactivated in the liver.
