Estudio molecular del reconocimiento maternal, adhesión y neovascularización en la peri-implantación ovina en dos tratamientos de sincronización del estro

Abstract

In the ewe, hormonal treatments based in progestagens are commonly used for estrus synchronization. However, poorer results have been demonstrated when compared to the natural cycle. In addition, there is a current controversy about the hormonal residues permitted in animal products in order to ensure consumers health. Thus, protocols based in prostaglandin analogues have been proposed as an alternative to progestagens for ovine cycle synchronization, although their apparent greater efficiency is still under revision. The present Doctoral Thesis focuses in the comparative study of both synchronization treatments during ovine early pregnancy, through the analysis of different elements involved in the uterine response to gestation establishment and periimplantation period, which encloses maternal recognition of pregnancy, conceptus adhesion and beginning of placentation. To fulfil this objective, post-ovulatory plasma concentration of progesterone was determined until day 21 post-coitus (pc) in a flock of ewes either synchronized with progestagens (Group P) or with prostaglandin analogues (Group PG), along with progesterone receptor (PR), Type I Interferon receptor (IFNAR), estrogen receptor-alpha (RE-α) and oxytocin receptor (OTR) immunoexpression in different cellular compartments of the pregnant uterus within days 9 to 21pc. Furthermore, expression of both immunoreactive L-Selectin adhesion molecule and its ligand CD34 have been assessed, as well as the positivity of Vascular endothelial growth factor (VEGF), CD31 and von Willebrand Factor (vWF) in endometrial caruncular vessels within days 15 to 21pc. Plasma progesterone was higher in Group PG, especially on days 10 y 16pc (P<0.05), which could enhance uterine preparation to pregnancy and embryo development. Moreover, progesterone levels rose significantly on days 1pc (P<0.05), 3pc (P<0.05), 8pc (P<0.01) y 9pc (P<0.001) in both groups of treatment, to keep arising less notoriously until day 21pc. Although PR demonstrated an interaction day x treatment in the caruncular stroma (P=0.027) and myometrium (P=0.000), its pattern of expression was similar in both treatments. RP decreased in all uterine compartments from day 9 to 21pc (P<0.01), with the exception of the caruncular stroma, where it increased, P<0.01, and the non caruncular stroma, deep stroma and myometrium, where PR expression was sustained. Stronger IFNAR immunoexpression in the non caruncular luminal epithelium was demonstrated in the PG group (P=0.05), which could be translated in a higher sensitivity to the increasing IFN-τ levels. In opposition to the glandular compartments, IFNAR varied significantly in the luminal epithelium (caruncular and non caruncular) of both treatments when comparing days of pregnancy (P<0.05). This could be related to the close contact that this compartment maintains with the embryo during implantation ...