Treatment of experimentally induced uterine adenomyosis with mifepristone (RU486)

Objective: To investigate the effectiveness of Mifepristone (RU486) on experimentally induced uterine adenomyosis in SHN mice. Methods: A single pituitary was transplanted in the lumen of the right uterus of 20 virgin female SHN mice at the age of 7 weeks respectively , as pituitary grafting quickly induced the development of uterine adenomyosis. Mice were randomly divided into 2 groups, 10 of each, 17 weeks after pituitary grafting. The treatment group received 4 weeks of RU486 treatment. All mice were then killed and the uteri and ovaries were weighed. The right uteri were examined under a 20 fold microscope and counted for the extrauterine nodules, which was the characteristic of advanced adenomyosis. Results: Uteri in treatment group were thinner and less congestive compared with those of the control group. Compared with the controls, RU486 treatment significantly reduced the uterine wet weight. The number of extrauterine nodules detected in each of the 8 mice in either group was significantly lower in RU486 treated group than that of the controls, although the incidence was similar between the two groups. Microscopic examination confirmed that all uteri showing extrauterine nodules were with advanced adenomyosis. In RU486 treated mice, the endometrial stromal cells became dense and the secretion activity of ectopic endometrial glands was markedly suppressed compared with the control group. The incidence of uterine adenomyosis was similar between RU486 treated group (8/10 mice, 80%) and the control group (8/10 mice, 80%). Conclusion: Four weeks of RU486 treatment shrunk the uterus and suppressed its adenomyosis in a mouse model although it could not cure the disease.