Date of Award

12-2006

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Animal Science

Major Professor

Frank Neal Schrick

Committee Members

J. L. Edwards, G. M. Pighetti, P. K. Tithof, T. M. Prado

Abstract

Prostaglandin F (PGF) 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 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 and to determine FPr mRNA and protein in bovine embryos. Prostaglandin F 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 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 effects on pre-compacted embryos was investigated. Results showed that addition of AL-8810 to the culture medium inhibited PGF 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 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 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.

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