Proteins secreted by the sheep conceptus suppress induction of uterine prostaglandin F-2  release by oestradiol and oxytocin

Kb, Fincher; Fw, Bazer; Pj, Hansen; Ww, Thatcher; Rm, Roberts

doi:10.1530/jrf.0.0760425

Cited by 77 publications

(33 citation statements)

References 21 publications

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“…(Goff et al, 1993), suggest that factors produced by the horse embryo cause the inhibition of PGF2n release indepen¬ dent from the density of endometrial oxytocin receptors. By contrast, in ovine and bovine species, suppression of oxytocin receptors (Sheldrick and Flint, 1985;Fuchs et al, 1990) coincides temporally with conceptus-induced inhibition of PGF2(1 synthesis Fincher et al, 1986;Spencer and Bazer, 1996). The (Warr and Branda, 1983), and there is evidence that the binding affinity of oxytocin to myometrial membranes is critically dependent on the concentration of cholesterol in the plasma membrane (Fahrenholz et al, 1995 (Fuchs et al, 1990) were observed: these included lower affinity to isotocin and higher affinity to oxytocin antagonists than in bovine endometrium, and complete lack of binding of the VP2-receptor subtype specific agonist.…”

Section: Plasma Oxytocinmentioning

confidence: 82%

Relationship between endometrial oxytocin receptors and oxytocin-induced prostaglandin F2 release during the oestrous cycle and early pregnancy in pony mares

Sharp

Thatcher²,

Salute³

et al. 1997

Reproduction

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Section: Plasma Oxytocinmentioning

confidence: 82%

Relationship between endometrial oxytocin receptors and oxytocin-induced prostaglandin F2 release during the oestrous cycle and early pregnancy in pony mares

Sharp

Thatcher²,

Salute³

et al. 1997

Reproduction

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“…These results confirm previous reports [13,23,24,65] suggesting that expression of endometrial ER, PR, and OTR genes is altered by signals from the conceptus. Doses of exogenous oxytocin or estrogen, which initiate luteolysis in cyclic ewes and cows, fail to cause luteolysis in pregnant ewes or in ewes receiving intrauterine injections of interferon-tau (IFN-T) [19,29,33,35,[66][67][68]. This phenomenon is attributable to very low or absent ER [12,23] and OTR in the endometrium of pregnant ewes [13,37,63,69].…”

Section: Discussionmentioning

confidence: 99%

Temporal and Spatial Alterations in Uterine Estrogen Receptor and Progesterone Receptor Gene Expression During the Estrous Cycle and Early Pregnancy in the Ewe1

Spencer

Bazer

1995

Biology of Reproduction

289

208

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Mechanisms regulating responses of the ovine uterus to endocrine and paracrine signals during the estrous cycle and pregnancy are likely to require tissue- and cell-specific regulation of steroid hormone receptor gene expression. To determine effects of day and pregnancy status (cyclic or pregnant) on uterine estrogen receptor (ER) and progesterone receptor (PR) gene expression, ewes were hysterectomized either on Day 1 (Day 0 = estrus/mating), 6, 11, 13, or 15 of the estrous cycle (n = 3/day) or on Day 11, 13, 15, 17, or 25 of early pregnancy (n = 5/day). Steady state levels of ER and PR mRNA were determined in endometrial and myometrial tissues by slot-blot hybridization and ribonuclease protection assays, respectively, using homologous ovine ER and PR cRNA probes. Changes in spatial expression of ER and PR mRNA and protein in uterine tissue sections were determined by in situ hybridization and immunocytochemical analyses. In cyclic ewes, steady state levels of endometrial ER mRNA were highest on Day 1, declined between Days 1 and 6, and increased between Days 11 and 15. However in pregnant ewes, endometrial ER mRNA levels decreased between Days 11 and 15 and increased slightly between Days 15 and 25. In cyclic ewes, levels of myometrial ER mRNA were highest on Day 1, decreased to Day 6, and remained low thereafter. In cyclic ewes, endometrial PR mRNA levels were highest on Day 1, decreased between Days 1 and 11, and then increased between Days 13 and 15. In cyclic ewes, myometrial PR mRNA levels were highest on Day 1 and declined thereafter. Endometrial PR mRNA levels were not different between cyclic and pregnant ewes on Days 11, 13, and 15. In pregnant ewes, PR mRNA levels were low on Day 11, increased between Days 11 and 17, and decreased between Days 17 and 25. In pregnant ewes, myometrial PR mRNA levels were low and did not change between Days 11 and 25. In situ hybridization and immunocytochemical analyses revealed distinct tissue- and cell type-specific alterations in uterine ER and PR mRNA and protein expression during the estrous cycle and early pregnancy that generally paralleled overall changes in steady state levels of ER and PR mRNAs. In the endometrium, the most striking observation was that PR mRNA and protein expression disappeared from the luminal and shallow glandular epithelium between Days 6 and 13 of the estrous cycle, whereas ER mRNA and protein expression was low on Days 6 and 11 and increased between Days 11 and 15 in the luminal and shallow glandular epithelium. During early pregnancy, expression of ER and PR mRNAs, as well as ER and PR protein, was very low or absent in the luminal and shallow glandular epithelium between Days 13 and 25 of pregnancy. Moreover, ER and PR mRNA and protein were consistently present at low levels in the stroma and deep glandular epithelium in both cyclic (Days 11-15) and pregnant (Days 11-25) ewes. Collectively, results suggest that uterine ER and PR gene expression is regulated in a tissue- and cell type-specific manner during the estrous cycle and early...

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“…In 1982 a protein was identified that was secreted into the medium when sheep conceptuses were cultured in vitro.|6' The synthesis of this protein appeared limited to the critical day [13][14][15][16][17][18][19][20][21] period when maternal recognition of pregnancy was mediated. The protein was later named oTP-1.…”

Section: Robertsmentioning

confidence: 99%

A Novel Group of Interferons Associated with the Early Ovine and Bovine Embryo

Roberts

1989

Journal of Interferon Research

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Recently, two proteins, ovine trophoblast protein-1 (oTP-1) and bovine trophoblast protein-1 (bTP-1), that are major products of the preimplantation ovine and bovine embryo, respectively, have been shown to be interferons (IFNs). Both proteins belong to an IFN-a subfamily whose polypeptide chains are 172 amino acids long. oTP-1 and bTP-1 have been strongly implicated in triggering maternal responses to the presence of a viable embryo and in maintaining pregnancy. Thus, a new and totally unsuspected role for a specific kind of IFN-a in the reproductive physiology of sheep, cattle, and possibly other species of mammal has become evident. Maternal recognition of pregnancyIn most mammals the lifespan of the corpus luteum of the ovary must be extended during pregnancy so that progesterone production will be continued. This steroid acts on the uterine lining, known as the endometrium, to maintain a milieu appropriate for the developing conceptus (the embryo plus its surrounding membranes). Therefore, the prevention of luteal regression is crucial and depends upon a chemical signal or signals that originate from the conceptus. This phenomenon, described as "maternal recognition of pregnancy," is one of a series of coordinated interactions that occurs between the conceptus and the mother as pregnancy proceeds.Hysterectomy (removal of the uterus) in ewes and cows and many other species, but not in primates, extends the lifespan of the corpus luteum for a period almost equivalent to the length of gestation.1" This persistence of the corpus luteum following hysterectomy indicates that the uterus is the source of the substance that causes luteal regression. Evidence has accumulated that the release of PGF2a by the uterus in the late luteal phase of the estrous cycle is the mechanism responsible for the destruction of the corpora lutea in domestic farm animals.'" In ewes, for example, the uterine endometrium begins to produce PGF2a on days 13 and 14 of the 17-day estrous cycle. At about that time, progesterone levels begin to fall and the animal returns to estrus (heat). In pregnancy, by contrast, the release of PGF2a is attenuated, and the corpus luteum continues to function.Until recently the nature of the conceptus products(s) involved in the rescue of the corpus luteum remained obscure. It was known from embryo transfer experiments that the product must first be produced around days 12-13 because transfers to nonpregnant ewes up to that time frequently succeeded, and removal of embryos from pregnant ewes after that time delayed a return to estrus.1231 373 ROBERTS In addition, homogenates from day 14-15 conceptuses infused into the uterus could extend luteal function in nonpregnant ewes.'4' The active ingredient was sensitive to heat and protease treatment and was not produced by conceptuses much older than 21 days of age.'45' oTP-1In 1982 a protein was identified that was secreted into the medium when sheep conceptuses were cultured in vitro.|6' The synthesis of this protein appeared limited to the critical day 13-21 peri...

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Proteins secreted by the sheep conceptus suppress induction of uterine prostaglandin F-2 release by oestradiol and oxytocin

Cited by 77 publications

References 21 publications

Relationship between endometrial oxytocin receptors and oxytocin-induced prostaglandin F2 release during the oestrous cycle and early pregnancy in pony mares

Relationship between endometrial oxytocin receptors and oxytocin-induced prostaglandin F2 release during the oestrous cycle and early pregnancy in pony mares

Temporal and Spatial Alterations in Uterine Estrogen Receptor and Progesterone Receptor Gene Expression During the Estrous Cycle and Early Pregnancy in the Ewe1

A Novel Group of Interferons Associated with the Early Ovine and Bovine Embryo

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