Use of a murine endometriosis interna model for the characterization of compounds that effectively treat human endometriosis.

Endometriosis is a chronic, estrogen-dependent disease characterized by the presence of ectopic endometrium either in the pelvic cavity (endometriosis externa) or within the uterus (endometriosis interna, adenomyosis). Key symptoms are pelvic pain, dysmenorrhea and infertility. Established rodent animal models used for drug research in endometriosis have certain limitations. Since rodents do not menstruate, they cannot develop endometriosis externa spontaneously, but they suffer from endometriosis interna. There is growing evidence that human endometriosis externa and interna represent two faces of the same disease. Both are estrogen-dependent and respond to similar treatment paradigms. Here, we addressed the question whether a murine endometriosis interna model may also be suitable for the characterization of drugs employed in human endometriosis. We examined the effects of danazol, Faslodex and cetrorelix in SHN mice that developed endometriosis interna after pituitary grafting. The GnRH antagonist cetrorelix and the estrogen receptor antagonist Faslodex, which negatively interfered with estrogen-mediated signaling, completely inhibited endometriosis interna, whereas danazol, an androgenic progestin, showed significant therapeutic activity in the majority of SHN mice. We conclude that this murine endometriosis interna model may be a valuable complement to established endometriosis externa models to support drug research in human endometriosis.