Ovarian stimulation with GnRH agonist, but not GnRH antagonist, partially restores the expression of endometrial integrin β3 and leukaemia-inhibitory factor and improves uterine receptivity in mice

BACKGROUND: The impact of different ovarian stimulation (OS) protocols on endometrial receptivity remains controversial. In this study, the effects of different OS on the expression of endometrial integrin beta 3 subunit and leukaemia-inhibitory factor (LIF) during the implantation window and the implantation rate in mice were investigated. METHODS: Three OS protocols were used, involving either pregnant mare's serum gonadotrophin (PMSG) alone, PMSG plus GnRH agonist or PMSG plus GnRH antagonist. Uterus samples were collected at 48 h after OS or ovulation and were detected with immunohistochemistry, Western blot and RT-PCR analyses. Normal embryos at gestation day 4 were transferred into the uteri of mice in the control and OS groups. RESULTS: All OS groups showed a significant decrease in the expression of both the endometrial integrin beta 3 subunit and LIF during the implantation window and the implantation rate. Among the three OS groups, GnRH agonist-treated mice showed a higher endometrial integrin beta 3 subunit and LIF expression and a higher implantation rate. No significant difference was found in the measured indices between the GnRH antagonist and PMSG groups. CONCLUSIONS: OS may inhibit the expression of endometrial integrin beta 3 subunit and LIF and impair endometrial receptivity in mice. OS with GnRH agonist, but not GnRH antagonist, may partially restore the endometrial physiological secretion and improve uterine receptivity.