HOXA10 protein expression in the endometrium of normally menstruating women after receiving GnRH antagonist

Abstract Objective(s) To compare HOXA10 protein expression in the endometrium between natural control cycles and GnRH antagonist-treated cycles obtained during the window of implantation of normally menstruating women. Study design This study was conducted at the Department of Obstetrics and Gynecology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand. Thirty-five volunteers were recruited into this prospective, self-controlled study, which was divided into two cycles, the first a natural control cycle and the second a GnRH antagonist-treated cycle. The two cycles were separated by one resting cycle. In the GnRH antagonist-treated cycle, when the leading follicle was 15 mm, ganirelix (Orgalutran® ) 0.25 mg was administered daily. In both cycles, ovulation was induced when the largest follicle reached 18 mm in diameter. Finally, endometrial biopsy was performed on day 6 after documented ovulation, which corresponds to the window of implantation. Endometrial HOXA10 protein expression, a marker of endometrial receptivity, was analyzed by immunohistochemistry. The protein expression was compared between the two cycles regarding their percentage of immunostained cells and IHC-scores (percentage of stained cells × intensity of nuclear staining). Results HOXA10 protein was exclusively localized in the stromal compartment of the endometrium. The percentage of HOXA10 nuclear staining in the endometrium collected from GnRH antagonist-treated cycles was higher than that of the natural cycles, whereas the IHC-scores showed no difference between the two cycles. Conclusion(s) GnRH antagonists may have no effect on HOXA10 protein expression in the endometrium obtained during the implantation window of normally menstruating women.