The effects of GnRH analogues on endometrial receptivity: a comprehensive study.

PURPOSE: Endometrial receptivity is a critical determinant of successful embryo implantation and pregnancy. Gonadotropin-releasing hormone (GnRH) analogues are widely used in in vitro fertilization (IVF) but their effects on endometrial receptivity remain incompletely understood. This study aims to investigate the impact of GnRH analogues on endometrial receptivity through various in vitro models. METHODS: Endometrial samples were collected across various stages of the menstrual cycle. The expression of the gonadotropin-releasing hormone receptor (GnRHR) was analyzed and quantified. A 3D endometrial model was constructed, and effects of GnRH analogues on trophoblast adhesion, as well as on the expression of markers related to endometrial receptivity, were assessed. RESULTS: The results indicate that GnRHR expression is higher in epithelium in the secretory phase. However, no significant difference in the adhesion of trophoblast cell spheres to endometrial cells across different GnRH analogue concentrations was observed. GnRH analogues did not affect gene mRNAs expressions or protein levels either. Proteomic analysis revealed a downregulation of ITGAE in the antagonist regimen and an upregulation of FAAH2 in the agonist regimen. CONCLUSIONS: This study suggests that GnRH analogues at different physiological concentrations used in IVF protocols do not significantly impact primary markers of endometrial receptivity. However, the use of antagonist may have an adverse effect on endometrial receptivity. Further research is required to elucidate indirect mechanisms by which GnRH analogues might affect endometrial receptivity and IVF outcomes.