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MH Adams1 *, CY Adam1 *, KS Simpson1 *, KM Smith1 , KJ McDowell1 *
Department of Veterinary Science, University of Kentucky, Lexington, KY 1
Distribution of estrogen and progesterone receptor (ER and PR) mRNAs in the endometrium of cycling and early pregnant mares was determined. Endometrial biopsies were obtained from nonbred (NB) mares at estrus (E) and days 5, 10 and 15 following ovulation, and from pregnant (P) mares at days 10, 15 and 20 following ovulation (n=3 mares per day). In situ hybridization for ER and PR was performed on frozen tissue sections. Evaluations were performed by 5 independent observers who were not aware of the treatment groups, and hybridization was scored on a scale of 0 (no hybridization) to 4 (intense hybridization). When NB mares were compared to E mares, hybridization for ER mRNA decreased at d53 and d102 in surface epithelium (SE) and superficial glandular epithelium (SG), and at d101 and d151 in middle glandular epithelium (MG). When pregnant mares were compared with E mares, hybridization for ER mRNA decreased in MG and deep glandular epithelium (DG) at d154 and d204, and in SE and SG at all days1 tested. When compared to E levels, hybridization for PR mRNA decreased in SE at d10NB2, d10P1 and d20P2 and decreased in SG at d10NB1 and at all days2 of pregnancy tested. In MG and DG, PR mRNA hybridization decreased at d15P1 and d20P1. ER was positively correlated with serum progesterone in SE2, SG3, and MG1. PR was positively correlated with serum progesterone in SE1 and SG2. The changing distributions of steroid receptors in mare endometrium may be important for the function of the tissue in varying reproductive states. 1p<0.05; 2p<0.01; 3p<0.001; 4p<0.0001.
This abstract is being presented on Tuesday, August 3 at 8:00 AM to 10:15 AM at CUB 2nd Floor Ballroom.