Oxytocin antagonism reverses the effects of high oestrogen levels and oxytocin on decidualization and cyclooxygenase activity in endometrial tissues

Abstract

Research question: What is the in-vitro effect of oxytocin receptor (OTR) antagonism on parameters of receptivity in human endometrial explants and endometrial stromal cell lines cultured in oestradiol-rich conditions mimicking ovarian stimulation?

Design: Experimental in-vitro study on endometrial tissue explants collected by aspiration biopsy from 30 women undergoing fertility treatment and cultured endometrial tHESC cell line. The study examined the effects of high oestradiol, oxytocin and OTR antagonist on parameters of decidualization (cell viability and prolactin secretion) as well as cyclooxygenase-1/2 (COX-1/2) activity and prostaglandin F_2α (PGF_2α) secretion. Changes in expression of OXTR and COX-2 genes were examined using quantitative polymerase chain reaction (qPCR).

Results: In experiments on cultured endometrial cell line, high oestradiol and oxytocin similarly limited the viability of cells. In cultured endometrial explants both also decreased the secretion of prolactin (a marker of decidualization) and augmented endometrial COX-2 activity and formation of PGF_2α. Oxytocin antagonist atosiban was confirmed to reverse the above effects, both in the endometrial line and endometrial explants. Addition of atosiban to cultures acted analogously in experiments employing both oxytocin and high oestradiol.

Conclusions: Oxytocin antagonist reversed the effects of high oestradiol and oxytocin on parameters related to endometrial receptivity in conditions mimicking ovarian stimulation. This might point to a novel, endometrium-related mechanism to support embryo implantation achieved by the application of oxytocin antagonist prior to embryo transfer.

Keywords: Decidualization; Embryo implantation; Endometrial receptivity; Ovarian stimulation; Oxytocin antagonist.