Principal Investigator: Mariana Diel de Amorim

DESCRIPTION (provided by applicant): 

The regulatory factors involved in pregnancy recognition in mares are uncertain, however closing these knowledge gaps is key to improving pregnancy outcomes. Pulsatile secretion of prostaglandin F by the equine endometrium induces luteolysis at around day 14 post-ovulation. Embryonic PGE secretion is important for tubal transport, embryo mobility and luteal function. Our preliminary data show that exogenous PGE is absorbed into the circulation from the uterus in non-pregnant mares. We hypothesize that there will be differences in PGE profiles of diestrus and pregnant mares. Mares (n=6) will be monitored daily in estrus using transrectal palpation and ultrasound to determine the day of ovulation (D0) and pregnancy status (D12). Mares will be studied in 2 cycles, a pregnant and diestrous cycle. Mares will be bred in estrus by a proven fertile stallion. A jugular catheter will be inserted on day 12.5 and blood drawn every hour from day 13 – 15. Plasma will be separated and stored frozen at -80C until assay. Commercial PGEM ELISA kits (Cayman Chemical) will be utilized for measurement of PGEM in the hourly samples. Plasma progesterone levels will be measured in the 8 am, and 8 pm samples by radioimmune assay (RIA). Data will be analyzed at P<0.05 for progesterone level, area under the curve and number of PGE peaks D13-15 post-ovulation. This basic information will assist in determining if PGE is one of the signals for pregnancy recognition in mares.