GnRH-I – A SUITABLE BIOMARKER FOR ASSESSMENT OF ENDOMETRIAL RECEPTIVITY
TODOR CHAUSHEV1*, DIMITAR PARVANOV1, GEORGI STAMENOV1, BALIK DZHAMBAZOV2
1 – Nadezhda Women’s Health Hospital, 3 “Blaga vest” Street, Sofia, Bulgaria
2 – Department of Developmental Biology, Plovdiv University “Paisii Hilendarski”, Plovdiv, Bulgaria
*Corresponding author: todor_chaushev@yahoo.com
Keywords: GnRH-I, human endometrium, endometrial receptivity, implantation window
Abstract: The hypothalamus and the pituitary gland are the main source and target sites of gonadotropin releasing hormone (GnRH), but numerous studies have demonstrated that GnRH-I and GnRH-II exist in different reproductive tissues such as the ovary, endometrium etc. Major effects of GnRH-I in the reproductive tissues are regulation of cell proliferation, activation of apoptosis and remodulation during the process of embryo implantation.
In this retrospective study, endometrial samples were obtained from 30 women with normal menstrual cycles. They were divided into two groups: (1) women with successful implantation (n=15) and (2) women with recurrent implantation failure (RIF) and unsuccessful implantation (n=15). The endometrial biopsies were dated histologically and immunohistochemically by using available criteria in the literature. Using immunohistochemistry, we identified GnRH-I in stromal, luminal and glandular epithelial cells.
Our results show that GnRH-I is expressed in different cell types of the human endometrium during the mid-luteal phase (window of implantation) – luminal epithelial cells, glandular epithelial cells and stromal cells. Considerably higher expression of this hormone in the patients with successful implantation was detected in the gland (Group 1 - 2.07 vs. Group 2 - 1.75, P = 0.042) and luminal epithelial cells (Group 1 - 2.05 vs. Group 2 - 1.73, P = 0.049). While only 30% of the patients with unsuccessful implantation had values for glandular epithelial cells H≥2, in the patients with successful outcome more than 70% exceeded this value.
As a conclusion an insufficient expression of GnRH-I in human endometrium during the mid-luteal phase could be related to embryo implantation failure. The immunohistochemical detection of GnRH-I expression should be considered as a suitable biomarker for assessment of endometrial receptivity during the window of implantation.