Local levonorgestrel regulation of androgen receptor and 17beta-hydroxysteroid dehydrogenase type 2 expression in human endometrium

The levonorgestrel-releasing intrauterine system (LNG-IUS) is a highly effective contraceptive. However, unscheduled breakthrough bleeding (BTB), leads to discontinuation in a proportion of users. The LNG-IUS down-regulates endometrial progesterone and estrogen receptors and this may play a role in the mechanism responsible for BTB. LNG is an androgenic progestogen and so we examined the regulation of the androgen receptor (AR) in endometrium exposed to intrauterine LNG. Furthermore, as the enzyme 17beta-hydroxysteroid dehydrogenase type 2 (17betaHSD2) regulates intracellular levels of estrogens, progestins and androgens, we evaluated the changes in expression of 17betaHSD2 in the same tissue endometrial samples.