The debate exists whether or not gonadotropin-releasing hormone (GnRH) analogs used in controlled ovarian hyperstimulation (COH) impair endometrial receptivity.Homeobox A11 (Hoxall),Meis homeobox 1 (Meisl),cadherin 1 (Cdhl),and catenin beta 1 (Ctnnbl) are well known to be involved in successful implantation.In this study,the endometrial expression of Hoxall,Meisl,Cdhl,and Ctnnbl during the peri-implantation period was investigated in an in vitro fertilization (IVF) mouse model by real-time RT-PCR and West blot to evaluate the relationship between Hoxall,Meisl,Cdhl,and Ctnnbl expression and the impact of the COH on endometrial receptivity.The mimic COH protocols included GnRH agonist plus human menopausal gonadotropin (HMG) (GnRH agonist group),GnRH antagonist plus HMG (GnRH antagonist group),and HMG alone (HMG group).The expression levels of Hoxall,Meisl,Cdhl,and Ctnnbl mRNA and protein were decreased in all of the COH groups.The expression levels of Hoxall and Ctnnbl were the lowest in the GnRH agonist group,and those of Meisl and Cdbl were lower in the GnRH analog groups than the HMG group.There were positive correlations between the expression of Hoxall and Ctnnbl,as well as the expression of Meisl and Cdhl among all the groups.In conclusion,the COH protocols,particularly with GnRH analogs,suppressed Hoxall,Meisl,Ctnnbl and Cdhl expression,in mouse endometrium during the peri-implantation period.Our data reveal a novel molecular mechanism by which the COH protocols might impair endometrial receptivity.