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 PARENT SESSION
FEMALE REPRODUCTIVE TRACT - B
Wednesday, August 4, 2004
10:30 AM–12:30 PM
Buchanan Courtyard
(806) EFFECT OF INTERFERON TAU ON PROSTAGLANDIN BIOSYNTHESIS, TRANSPORT, AND SIGNALLING DURING MATERNAL RECOGNITION OF PREGNANCY IN CATTLE: EVIDENCE OF POLYCRINE ACTION OF PGE2.
Banu, Sakhila1, Arosh, Joe1, Kimmins, Sarah2, Chapdelaine, Pierre1, MacLaren, Leslie2, Fortier, Michel3, 1 Unité d' Ontogénie et Reproduction, CHUL, CRBR, Université Laval, Québec, PQ, Canada2 Departments of Plant and Animal Sciences, Nova Scotia Agricultural College, Truro, Nova Scotia, Canada3 Départment d' Obstetrique et Gynecologie, Université Laval, Quebec, PQ, Canada
ABSTRACT- Recognition and establishment of pregnancy involve several molecular and cellular cross talks between the conceptus, uterus, and corpus luteum (CL). In ruminants, interferon tau (IFNt) of embryonic origin is recognized as the pregnancy recognition signal. Endometrial PGF2 is the luteolysin while PGE2 is considered as a luteoprotective mediator at the time of establishment of pregnancy. The interplay between IFNt and endometrial PGs production, transport and signaling is not well understood during maternal recognition of pregnancy (MRP). We have studied the expression of enzymes involved in the metabolism of PGE2 and PGF2, cyclooxygenase (COX) 1 and 2, PG synthases (PGES and PGFS), prostaglandin 15-dehydrogenase (PGDH), and PG transporter (PGT) as well as receptors (EP2, EP3 and FP) in endometrium, myometrium, utero-ovarian plexus and CL during MRP in cattle. Beef heifers (19 + 1 day cycle) were used. Estrus was synchronized with double PGF2 regimen. On day 14 ovine rIFNt (0.25 mg/dose) and 0.1% BSA (4 doses at 12 h intervals) were infused intrauterine in treatment and control groups (n=3), respectively. On day 16 animals were slaughtered and tissues were collected. Expression analyses were performed using LightCycler, Northern and Western blots. Our results show that IFNt influences cell-specific expressions of COX-2, PGFS, EP2 and EP3 in endometrium, myometrium and CL in a spatio-temporal and tissue-specific manner whereas it does not alter COX-1, PGES, PGDH, PGT and FP expressions in any of these tissues. In endometrium, IFNt decreases PGFS in epithelial cells and increases EP2 in stroma. In myometrium, IFNt decreases PGFS and increases EP2 in smooth muscle cells. In CL, IFNt increases PGES and decreases EP3. Together, our results suggest that IFNt directly or indirectly increases PGE2 production and EP2 signaling in endometrium, myometrium and CL during MRP. The increased endometrial PGE2 may play pivotal roles in endometrial receptivity, myometrial quiescence and luteal maintenance through auto-, para- and endocrine actions. Therefore, establishment of pregnancy may not only depend on inhibition of endometrial PGF2 but also on increased PGE2 production in cattle. Collectively, our findings point at a polycrine action of PGE2 in uterus and corpus luteum during the process of MRP in cattle.
KEY WORDS: PG receptors, MRP and Cattle, PG metabolic enzymes, PG transporter
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