Everolimus as an mTOR Inhibitor Suppresses Endometriotic Implants: an Experimental Rat Study

Introduction Mammalian target of rapamycin is a pathway to block apoptosis. Recent studies showed that the activity of mammalian target of rapamycin pathway increases in endometriotic lesions. Aim of the present study was to study the effect of everolimus agent, a rapamycin analog, in an experimental endometriosis model. Materials and Methods Endometriosis established by the autotransplantation of uterine tissue in the peritoneal cavity was confirmed in 24 rats. The animals were then randomly divided into three groups to receive either everolimus (1.5 mg/kg/day, p. o.), anastrozole (0.004 mg/day, p. o.), or normal saline (0.1 mL, i. p.) for 14 days. Endometriotic foci were excised, stained with hematoxylin and eosin, and endometriosis was scored semiquantitatively. In addition, immunohistochemical examination were performed using primary antibodies of vascular endothelial growth factor, CD117, and Bax. Results Both anastrozole and everolimus lowered endometriosis scores. Significant decreases in ovarian follicles were observed following anastrozole treatment but not everolimus treatment. Conclusion Through its apoptosis-promoting effect, everolimus suppressed endometriotic foci without negatively affecting ovarian reserve. These findings support the hypothesis that everolimus merits further study on the way to developing a new endometriosis drug.