The ovarian stimulation effects on Muc1 expression of the mouse endometrium before implantation
The ovarian stimulation effects on Muc1 expression of the mouse endometrium before implantation
azam soleimani,1,*
1. Kazerun Medical Sciences Branch, Islamic Azad University, Kazerun, Iran
Introduction: The implantation process involves complex and synchronized molecular and cellular events between the uterus and the implanting embryo. Implantation occurs only during a certain time in pregnancy referred to as the window of implantation. The opening of this window and process of implantation are known to be controlled by ovarian steroid hormones. The receptive status of the Endometrium in embryonic implantation is a balance between the activation of adhesion molecules and the presence of a barrier that the embryo may encounter on the endometrial epithelium. The nonreceptive uterus maintains a thick glycocalyx on the apical surface of luminal epithelial cells. Within this carbohydrate mixture is a transmembrane mucin, mucin-1 (Muc1). Muc1 is an extremely large (>200 kDa), heavily glycosylated molecule that is proposed to extend much farther from the luminal surface than other components of the apical glycocalyx. Sex steroids can be involved in the regulation of Muc1 transcription either by directly interacting with the Muc1 promoter or indirectly by stimulating or repressing of the transcription factors.The purpose of this study was to investigate the alterations on Muc1 expression of the mouse endometrium after hyperstimulation using HMG and HCG injections. Therefore, a careful evaluation of the regulation of Muc1 at the endometrial surface is necessary.
Methods: The paraffin-embedded tissues were sectioned to a thickness of 5 μm. Sections were then deparaffinized in xylene, dehydrated in a series of ethanol solutions and stained using standard immunohistochemistry procedures. Tissue sections were pretreated by boiling in 10 mmol/L citrate buffer (pH 6.0) for 15 min as recommended by the supplier. For immunohistochemical detection of Muc1, CT1 polyclonal antibody (sigma, USA) at dilution of 1:200 was used, then incubated with alkalin phosphatas conjugated secondary antibody (abcam, ab5746) (1:100 dilution in TBS) for 1 hour. The antibodies were visualized by incubating with NBT/BCIP cromogen (Roche) for 10 min. Staining intensity of tissue sections was evaluated and graded. The sections were then counterstained with hematoxylin rinsed in tap water and mounted. The positive controls were used by breast cancer samples.
Results: In this study, Immunoreactivity was scored according to the tensity of staining and statistic analysis didn’t perform. Immunoreactivity was graded as – (negative), ± (trace positive), + (positive), ++ (moderately positive) or +++ (strongly positive).The samples were scored by two independent observers, and slides with discordant interpretations were examined by both observers together until a consensus was reached. As expected, staining was restricted to the apical aspects of luminal and glandular epithelial cells. Our data showed that the levels of Muc1 associated with the uterine epithelia are reduced by the time of implantation of the blastocyst. Ovarian hyperstimulation didn’t alter the Muc1 expression markedly in surface and glandular epithelium, which could affect on its receptivity.
Conclusion: In the present study we demonstrated, in the control and hyperstimulation groups the Muc1 expression is markedly reduced in the luminal uterus epithelium at the time of implantation. Our results are consistent with the existing viewpoint that endometrial expression of Muc1 positively correlates with endometrial receptivity and embryonic implantation. This loss of Muc1 protein is potentially due to the action of steroid hormones. In addition, our results showed that ovarian hyperstimulation didn’t alter the Muc1 expression markedly in surface and glandular epithelium, which could affect on its receptivity.