Inhibition of Direct Prostaglandin F_2α Effects on Pre-attachment Embryos Improves Reproductive Efficiency in Cattle

Prostaglandin F_2α (PGF_2α) has been shown to have detrimental effects on embryonic development, quality and hatching ability of embryos and pregnancy rates in cows. However, information about PGF_2α receptor (FPr) mRNA and protein in the preattachment bovine embryo is absent in the literature. The first experiment was design to identify the period of time during in vitro embryo development that is most susceptible to PGF_2α and to determine FPr mRNA and protein in bovine embryos. Prostaglandin F_2α decreased development of embryos to compact morula, but had no effect on development to blastocyst. In addition, FPr mRNA and protein was confirmed by real time PCR and Western Blot analysis, respectively, suggesting that PGF_2α is having a direct negative effect on in vitro development of bovine embryos by activating its receptor.

Discovery of FPr in bovine embryos allowed for development of new therapeutic strategies aimed at improving reproduction in bovines. Therefore, in a second experiment, the effects of a selective FPr antagonist, AL-8810, on in vitro development of bovine embryos was evaluated. The antagonist did not have toxic effects on development of embryos. Subsequently, efficacy of AL-8810 to prevent PGF_2α effects on pre-compacted embryos was investigated. Results showed that addition of AL-8810 to the culture medium inhibited PGF_2α effects on development to morula stage.

In a third experiment, embryonic development and gene expression of Na⁺/K⁺ ATPase α1 and zonula occludens-1 (ZO-1), two important genes participating in blastocyst formation and hatching, was examined after culture of in vivo-derived frozen/thawed bovine embryos with AL-8810, PGF, AL-8810+PGF, or Control. Thereafter, pregnancy rates of embryos recovered with medium containing AL-8810 was evaluated. Results indicated that AL-8810 inhibited negative effects of PGF_2α on development of embryos; however, no differences in gene expression were observed. Furthermore, recovery of embryos with medium containing AL-8810 improved pregnancy rates following transfer to recipient cows. In conclusion, inhibition of PGF_2α binding to its receptors on in vitro- and in vivo-derived bovine embryos increases embryonic development and pregnancy rates after transfer to recipient animals; respectively. These findings will likely increase efficiency of in vitro production of embryos and embryo transfer programs in cattle.