109 EXPRESSION OF GENES RELATED TO ENDOMETRIAL RECEPTIVITY IN EQUINE ENDOMETRIUM DURING THE ESTROUS CYCLE AND EARLY PREGNANCY

Abstract

A set of genes that display differential expression levels in the reproductive tract could serve as beneficial markers of endometrial receptivity. SERPINA14 is present in the uterus during pregnancy and suppresses lymphocyte accumulation. Osteopontin is the ligand of integrin β3 and enables trophoblast communication during implantation. Leukemia inhibitory factor (LIF) is involved in inflammatory cell signalling and contributes to implantation by regulating immune cells. The objective was to assess the expression of SERPINA14, osteopontin, and LIF mRNAs in the equine endometrium during the oestrous cycle and early pregnancy. Biopsies were obtained from mares on day of ovulation (d 0, n = 4), late diestrus (LD, n = 4, high progesterone [P4]), and after luteolysis at the beginning of oestrus phase (AL, n = 4, <1 ng mL^–1 P4) of the cycle. Biopsies were also taken on days 14 (P14, n = 4), 18 (P18, n = 4), and 22 (P22; n = 4) of pregnancy. Relative mRNA expression levels of genes were quantified using real-time quantitative RT-qPCR in duplicate. Data were analysed using one-way ANOVA, and l.s.d. test was applied. Both the oestrous cycle and early pregnancy increased SERPINA14 mRNA levels compared to d0. Expression of LIF mRNA was not significantly regulated except for a decline at AL. Expression of osteopontin mRNA was up-regulated during the oestrous cycle at LD while early pregnancy inhibited this up-regulation. The results suggest that the genes studied related to endometrial receptivity are strictly regulated accordingly to the stage of oestrous cycle, probably by circulating ovarian steroids, specifically progesterone, and pregnancy-associated factors are also involved in this regulation.

This project was partially funded by TUBITAK 107O035 to AG and DUBAP 14VF12 to MOA. MH was supported by OYP 2013-090.