Effect of Ovarian Stimulation on the Endometrial Apoptosis at Implantation Period

Apoptosis is a process that plays an important role during early stage of implantation. The aimof this study was to investigate the incidence of apoptosis in mice endometrium after ovarian stimulation atimplantation period. Methods: NMRI female mice were divided into two groups: 1) control group, whichwere rendered pseudopregnant by vaginal stimulation and 2) experimental group, which were stimulated usingan intrapritoneal injection of 10 IU hMG followed by another injection of 10 IU hCG after 48 h. In theevening of the second injection, the mice were rendered pseudopregnant the same as control group. Sampleswere obtained from 1/3 middle part of uterine horns during implantation period. Apoptosis was assessed intwo groups at implantation period using light and electron microscopic studies, TUNEL staining andsemiquantitative RT-PCR. Results: Our morphological and ultrastructural results showed apoptosis in bothgroups, while TUNEL analysis showed that the percentage of TUNEL-positive cells was higher in stimulatedgroup than in the control group (P≤0.05). The expression of P53, Fas and FasL mRNA was similar in twogroups but Bax and Bcl2 were much higher in control group than in the stimulated group (P≤0.05). The ratioof Bax/Bcl2 expression was much higher in stimulated group than in the control group (P≤0.05). Conclusion:The ovarian stimulation could change the expression of some apoptosis-related genes and enhance theincidence of endometrial apoptosis at implantation period; thus, it could affect on the implantation rate andendometrial receptivity