Melatonin implants in spring improve embryo production of aged ewes after superovulation regardless of endometrial progesterone receptor expression

ABECIA, J. A.; MEIKLE, A.; VÁZQUEZ, M. I.; CASAO, A.; FORCADA, F.; SOSA, C.

REPRODUCTION FERTILITY AND DEVELOPMENT

CSIRO PUBLISHING

Lugar: Collingwood; Año: 2019 vol. 31

1031-3613

Twenty-three Rasa Aragonesa aged ewes (average age: 10.3 years) were used to determine the effect of melatonin implants on the ovulatory response, embryo production, and the endometrial expression of progesterone receptors (PR) after superovulation. Ewes were treated (M, n=13) or not (C, n=10) with melatonin implants in March (day 0). All of them received intravaginal progestogen sponges for 14 days on day 77. Superovulatory treatments consisted of 8 doses in decreasing concentrations (2 mLx2 and 1 mLx6) of 176 NIH-FSH-S1 units of NIADDK-oFSH-17 administered twice daily starting 72 h before sponge removal. Seven days after the onset of estrus, embryos were recovered by laparotomy. After embryos were collected, ewes were euthanized, and uterine horns were processed to study PR expression by immunohistochemistry. The amount of PR was estimated subjectively by two independent observers in five endometrial compartments: luminal epithelium (LE), superficial (sGE) and deep (dGE) glandular epithelia, and superficial (sS) and deep (dS) stroma. The extent of staining of each cell type was expressed in proportion on a scale of 0?100. Melatonin implants improved fertilization (92 vs. 57%, for M and C groups, resp., P