FEMALE REPRODUCTIVE TRACT - B
Wednesday, August 4, 2004
10:30 AM–12:30 PM
(814) ESTROUS CYCLE-DEPENDENT AND LOCAL REGULATED EXPRESSION IN THE BOVINE OVIDUCT OF KEY ENZYMES FOR PROSTAGLANDIN E2 (PGE2) SYNTHESIS INDICATES AN IMPORTANT ROLE FOR PGE2 FOR SUCCESSFUL FERTILIZATION.
Gabler, Christoph1, Odau, Simone1, Holder, Christoph1, Einspanier, Ralf1, 1 Institute of Veterinary-Biochemistry, Berlin, Germany
ABSTRACT- Fertilization and development of the early embryo occur in the mammalian oviduct which provides optimal conditions for these processes. Prostaglandins (PG) are present in the bovine oviduct playing an important role in muscle contraction or as survival factors. Key enzymes in the synthesis of prostaglandins are cyclooxygenases (COX) by converting arachidonic acid into PGH2. The PGE synthase (PGES) converts PGH2 into PGE2. Several PGE receptors (EP) are involved in mediating biological effects of PGE2. The aim of the present study was to investigate a possible local PGE2 synthesis by detecting mRNA of COX-1 and -2, PGES, EP-2 and EP-3 in different regions (ampulla and isthmus) of the bovine oviduct during the estrous cycle. Bovine oviducts were collected throughout the estrous cycle and classified into the following four phases: pre-ovulatory, post-ovulatory, early and late luteal phase. Oviducts were divided in ipsilateral (to ovulation/dominant follicle) and contralateral oviducts. Oviductal epithelial cells were harvested by flushing separately the ampulla and the isthmus. Total RNA was extracted and quantitative real-time RT-PCR was performed. Expression of COX-1 and -2, PGES, EP-2 and -3 mRNA was detected in all regions of the oviduct during the whole estrous cycle. Quantitative real-time RT-PCR revealed a significant twofold increase of COX-2 expression from the luteal phase to the post-ovulatory phase. After ovulation, the highest COX-2 mRNA expression was noted in the ipsilateral oviduct compared to the other side. The same expression pattern was observed for PGES with the highest expression after ovulation in the ipsilateral oviduct. COX-1 mRNA content increased twofold from the luteal to the post-ovulatory phase showing no regional differences. The highest EP-2 mRNA expression was detected in the pre-ovulatory phase compared to the luteal phase in contrast to EP-3 which showed no estrous cycle-dependent expression. The expression pattern of COX-2 and PGES suggests that an estrous cycle-dependent and region-specific synthesis of oviductal PGE2 is required for a successful reproduction. Therefore, we hypothesize that a local PG synthesis may directly influence survival and transport of the ovulated egg as well as of the early embryo. Supported by the DFG (Ei 296/10-1).
KEY WORDS: fertilization, oviduct, prostaglandin