Expression of enzymes involved in the synthesis of prostaglandin E2 in bovine in vitro-produced embryos

• Published in: Zygote (Cambridge) Vol. 19; no. 3; pp. 277 - 283
• Main Authors: Saint-Dizier, Marie, Grimard, Bénédicte, Guyader-Joly, Catherine, Humblot, Patrice, Ponter, Andrew A.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.08.2011
• Subjects: Animals; Biosynthesis; Blastocyst - cytology; Blastocyst - enzymology; Cattle; Dinoprostone - metabolism; Embryo, Mammalian - cytology; Embryo, Mammalian - enzymology; Female; Gene expression; In vitro fertilization; Intramolecular Oxidoreductases - genetics; Intramolecular Oxidoreductases - metabolism; Morula - cytology; Morula - enzymology; Oocytes - cytology; Oocytes - enzymology; Pregnancy; Prostaglandin H2 - genetics; Prostaglandin H2 - metabolism; Prostaglandin-E Synthases; Prostaglandin-Endoperoxide Synthases - genetics; Prostaglandin-Endoperoxide Synthases - metabolism; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - genetics; RNA, Messenger - metabolism; Transplants & implants; bovine; embryo; prostaglandin E2; COX; synthases
• ISSN: 0967-1994; 1469-8730
• DOI: 10.1017/S0967199410000596

Prostaglandin E2 (PGE2) may play a major role in embryo development and the establishment of pregnancy in cattle. The biosynthesis of PGE2 implies the sequential transformation of arachidonic acid to PGH2 by cyclooxygenases (COXs), then the conversion of PGH2 to PGE2 by prostaglandin E synthases (PGESs). Quantitative RT-PCR was used to examine the expression of COX-1, COX-2, microsomal PGES-1 (mPGES-1), microsomal PGES-2 (mPGES-2) and cytosolic PGES (cPGES) mRNAs in day 7 in vitro-produced (IVP) embryos from oocytes collected by ovum pick-up in Holstein heifers. Transcripts for COX-2 and mPGES-1 were detected in all embryos, whereas transcripts for COX-1 and mPGES-2 were not detected and cPGESs were at the limit of detection in 40% of embryos. Levels of COX-2 and mPGES-1 mRNAs were significantly higher in blastocysts and expanded blastocysts than in morulae and early blastocysts. Furthermore, excellent-quality embryos (grade 1) displayed higher levels of both COX-2 and mPGES-1 than did embryos of good and medium qualities (grades 2–3). Our results suggest that bovine IVP embryos at the morula and blastocyst stages use exclusively the COX-2/mPGES-1 pathway for PGE2 biosynthesis, and that PGE2 is potentially involved in blastocyst expansion and developmental competence.