Prostaglandin F(2α) (PGF(2α)) production possibility and its receptors expression in the early- and late-cleaved preimplantation bovine embryos

BACKGROUND: Prostaglandin F(2α) (PGF(2α)) is an important component for the physiology of female reproductive processes. In the literature, the data pertaining to the synthesis and action of PGF(2α) in early embryonic bovine development are limited. In our study, we used the bovine in vitro culture model based on the time of first cleavage to determine the mRNA expression and immunolocalization of PGF(2α) synthase and its receptor in bovine embryos from the 2-cell stage to the hatched blastocyst stage. We also evaluated PGF(2α) production at 2, 5 and 7 days of in vitro culture. RESULTS: We found a significantly higher proportion of blastocysts obtained from the early-cleaved embryos than from the late-cleaved embryos (37.7% vs. 26.1% respectively, P < 0.05). The PGFS mRNA expression was significantly higher in the late-cleaved group than in the early-cleaved group at the 2-, 4- and 16-cell stages (P < 0.05). For PTGFR, we observed that within the late-cleaved group, the mRNA abundance was significantly higher in embryos at the 2- and 16-cell stages than in embryos at the 4- and 8-cell stages (P < 0.05). We observed that PTGFR mRNA expression was significantly higher in the 2- and 16-cell embryos in the late-cleaved group than that in the early-cleaved group embryos (P < 0.05). Among the blastocysts, the PGFS and PTGFR expression levels showed a trend towards higher mRNA expression in the late-cleaved group than in the early-cleaved group. Analysis of PGF(2α) production showed that within the early-cleaved group, the content of PGF(2α) in the in vitro culture medium was significantly higher on day 7 than it was on day 2 (P < 0.05). CONCLUSIONS: The mRNA expression levels of PGF(2α) synthase and its receptor depend on the developmental stage and the embryo quality. Analyses of PGFS and PTGFR expression in bovine blastocysts and of PGF(2α) embryo production suggest that prostaglandin F(2α) can act in an autocrine and paracrine manner in bovine in vitro-produced preimplantation embryos. Moreover, the tendency of PTGFR and PGFS mRNA expression to be upregulated in embryos with low developmental potential can indicate a compensation mechanism related to high PGFS and PTGFR mRNA expression levels in low-quality embryos.