Estrogen receptor is expressed in pig embryos during preimplantation development

Abstract

Although estrogen is recognized as essential for embryonic development and maintenance of pregnancy, it remains unclear whether it has a direct role in the embryos themselves. The aim of this study was to investigate whether estrogen can have any effect in pig embryos during preimplantation development. Since the function of estrogen is mediated through its specific receptor, estrogen receptor (ER), the presence of ER mRNA and protein in pig embryos collected in vivo at different stages of preimplantation development was determined and compared. Using reverse transcription polymerase chain reaction, ER RNA was detected at the one-cell, two-cell, and four-cell stages. The level became undetectable at the five- to eight-cell stages and the morula stages and then reappeared again at the blastocyst stage. To determine whether the ER message observed in the embryos was translated into ER protein, immunocytochemical analysis was performed and the presence of ER protein was detected in oocytes at one-cell and four-cell stages. However, the amount of ER protein in porcine embryos at the blastocyst stage was still below the detection limit. The presence of ER mRNA at the blastocyst stages suggests that estrogen may start to act directly on pig embryos afterwards, and our results provide a basis for determining the direct role of estrogen in preimplantation pig embryos.

Differential expression profiling of estrogen receptor in the ovaries of two egg duck (Anas platyrhynchos) breeds

“…In contrast, ESR1 occurs mainly in the mammalian uterus (Byers et al, 1997;Couse et al, 1997;Drummond et al, 1999) and it is essential for female sexual differentiation, fertility, and lactation (Drummond et al, 2002). Previous studies showed that the physiological roles of estrogens in the ovary are mediated more by ESR2 than by ESR1 during early postnatal development (Ying et al, 2000;Nilsson et al, 2001;Kowalski et al, 2002;Ni et al, 2007). Therefore, this probably explains why the increase of ESR2 expression from the age of the first egg to 500 days was higher than that of ESR1.…”

Effect of Resveratrol on the Development of Porcine Embryos Produced In Vitro

“…The same study also demonstrated that resveratrol induced proliferation of various human cell lines by stimulating the estrogen receptor in a dose dependent manner. The estrogen receptor has long been implicated in the regulation of cellular development [35] and its expression was shown in preimplantation pig embryos [36]. In addition, in another report low concentrations (5-10 μM) of resveratrol induced S-phase entry and this pro-proliferation effect was limited to cells possessing androgen receptors [18].…”

Differentiation of murine embryonic stem cells induces progesterone receptor gene expression

“…In the developing mouse embryo, ERα, ERβ, and PR are expressed at the blastocyst stage and thereafter [16][17][18][19][20][21][22][23]. The expression of these receptors in mES cells may not directly reflect the same timing as in development, but their expression in mES cells allows us to use it as a model system of in vitro differentiation.…”

“…Other members of the nuclear receptor family, estrogen receptor alpha (ERα), estrogen receptor beta (ERβ), and progesterone receptor (PR) are present in the early developing embryo of mice and other species [16][17][18][19][20][21][22][23]. In particular, ERα is present in the oocyte, shows variable expression through the morula stage, followed by increased expression in the inner cell mass of the blastocyst.…”