Effects of mifepristone (RU486) treatment on the development of uterine adenomyosis induced by pituitary grafting in mice

To evaluate the effects of mifepristone (RU486) on the development of uterine adenomyosis induced by pituitary grafting (PG), 3 groups of mice receiving pituitary grafts at 7 weeks of age were given RU486 in food (20mg/kg chow) from 3-14 (RU486-3 group) or 10-14 (RU486-10 group) weeks of age, or were given no further treatment (PG control group), respectively. All the mice were killed at 14 weeks of age. The uterine weight was significantly decreased in both RU486-treated groups compared with the PG control group. The incidence of adenomyosis was also decreased significantly in both the RU486-3 group (0/10 mice) and RU486-10 group (2/10 mice) compared with the PG control group (7/9 mice). To look for vascular changes in the uterine tissues, which have been reported to be related to the development of adenomyosis, immunohistochemical staining of von Willebrand factor in the blood vessels was performed. The mean surface area and minor axis of blood vessels in the uterus were thereby found to be significantly decreased in the RU486-10 group compared to the PG control group. The results clearly indicated that RU486, a potent antiprogestin, could inhibit the genesis of uterine adenomyosis in mice, and at the same time caused shrinkage of the vascular system. As in humans, progesterone as well as the vascular system therefore appear to be important factors in the pathogenesis of uterine adenomyosis in this mouse model. (C) 2000 Elsevier Science Inc. All rights reserved.Medicine, Research & ExperimentalPharmacology & PharmacySCI(E)PubMed6ARTICLE222713-27206