Alteration of endometrial receptivity in rats with ovarian hyperstimulation syndrome

It is unclear if the higher pregnancy rate in patients who experience ovarian hyperstimulation syndrome (OHSS) indicates that OHSS is favourable for embryo implantation, or if patients should be maintained in a hyperstimulation state in order to increase the success rate of embryo transplantation. We developed an animal model to determine the endometrial receptivity in rats with OHSS. Endometrial mRNA levels of ER, PR, HOXA10 and LIF were determined by semi-quantitative PCR and ER, PR, HOXA10, LIF and integrin α(v) β(3) protein levels were determined by Western blotting. Development of pinopodes in the hyperstimulation group was slightly delayed, while in the regular stimulation group, development was significantly inhibited. mRNA transcription in the regular stimulation group was lower, while transcription in the hyperstimulation group was not different from controls. Protein expressions were lowest in the regular stimulation. We conclude that OHSS is associated with favourable endometrial receptivity, similar to that seen in a normal cycle, and receptivity that is increased relative to that seen with a routine stimulation protocol.