Prostaglandin F and E levels in the conceptus, uterus and plasma during early pregnancy in the ewe

Concentrations of prostaglandins E and F (PGE and PGF) were measured in the embryo or fetus, extra embryonic or fetal membranes (membranes), intercaruncular and caruncular endometrium and plasma collected from uterine and ovarian arterial and venous vessels from separate groups of ewes laparotomized at 5 day intervals from day 10 to day 55 of pregnancy. Our purpose was to investigate the role of prostaglandins E and F in the maternal recognition of pregnancy, implantation and early placental function. Our data suggest that the initial maintenance of the corpus luteum in the pregnant ewe does not involve a reduction in PGF production, compared to pregnant ewes; but a change in the pattern of PGF secretion. This is accompanied by an elevation in PGE production of similar magnitude to that observed in non pregnant ewes. The extra embryonic/fetal membranes appear to be the major source of elevated PGF levels in the maternal circulation prior to day 30 of pregnancy. Between days 35 and 55 of gestation the rising PGF levels in maternal serum probably come from the fetus. Over the same period PGE levels rise in the fetus and intercaruncular endometrium, but PGE secretion into the maternal circulation is not enhanced. A role for PGF and PGE in fetal, placental and uterine growth is suggested; placental and uterine endocrine function may also be targets.     

Expression of the orexin system in the porcine uterus,conceptus and trophoblast during early pregnancy

Orexin A and B are hypothalamic peptides derived from the prepro-orexin (PPO) precursor. Orexins stimulate food intake and arousal. Those peptides bind and activate two G protein-coupled receptors: orexin receptor 1 (OX1R) and orexin receptor 2 (OX2R). Numerous authors have suggested that orexins play an important role in the regulation of the reproductive functions. The objective of the present study was to analyse the presence of and changes in the gene and protein expression pattern of the orexin system in the porcine uterus, conceptus and trophoblast (chorioallantois) during early pregnancy. In the endometrium, the highest PPO and OX1R gene expression was detected on days 15 to 16 of gestation. The OX2R mRNA content in the endometrium was higher on days 10 to 11 and 15 to 16 than on days 12 to 13 and 27 to 28. In the trophoblasts, PPO gene expression was higher on days 30 to 32 than on days 27 to 28. The highest PPO protein content in the endometrium was noted on days 12 to 13. The highest OX1R protein content in the endometrium was detected on days 10 to 11, whereas OX2R protein on days 15 to 16. In the trophoblasts, PPO and OX1R protein levels were more pronounced on days 27 to 28 than on days 30 to 32, but OX2R expression was higher on days 30 to 32. The expression of PPO, OX1R and OX2R was different in the conceptuses and trophoblasts during early pregnancy. Local orexin production and the presence of the specific orexin receptors suggest that the orexin system may participate in the control of porcine reproductive functions by exerting endocrine and auto/paracrine effects on the uterus, conceptuses and trophoblasts during early pregnancy. This study provides the first evidence for the presence of orexins and their receptors in the uteri, conceptuses and trophoblasts in pigs during early pregnancy. The local orexin system is dependent on the stage of pregnancy.     

Localization of prostaglandin F in the ovine uterus during early pregnancy

As part of a study on the anti-luteolytic action of the sheep conceptus, the distribution of prostaglandin F (PGF) within the uteri of 19 pregnant and 14 non-pregnant ewes was studied using three antisera to PGF_2α and fluorescent antibody tracing. In the uteri of seven non-pregnant ewes up to Day 11 after estrus (Day 0) and in uteri of $\text{18}\text{19}$ pregnant ewes up to Day 50, PGF was localized mainly in the lamina propria, with very little on epithelial cells lining the uterine lumen. After Day 11, in the uteri of seven non-pregnant ewes, PGF was localized on the surface of luminal epithelial cells and throughout their cytoplasm, and to a lesser extent in the lamina propria. The distribution of PGF on Days 14 and 17 in the gravid and non-gravid horns of the uteri of 13 ewes made unilaterally pregnant (conceptus confined to one uterine horn) was similar to that described above for normal pregnant and non-pregnant ewes after Day 11 respectively.These results are interpreted to indicate a change in the distribution of PGF in sheep uteri due to the presence of a conceptus.     

Jugular levels of 13,14-dihydro-15-keto-prostaglandin F and progesterone around luteolysis and early pregnancy in the ewe

Six non-pregnant ewes at day 12 of the estrous cycle each had a day-12 embryo transferred into the uterine horn ipsilateral to the corpus luteum, and 4 non-pregnant ewes at day 13 each had a day-13 embryo similarly transferred. Four control ewes, 2 at day 12 and 2 at day 13 received sheep serum into the uterine horn ipsilateral to the corpus luteum. Jugular blood samples were taken at 2-hourly intervals for 3 days post-surgery, then twice-daily for a further 4 days, and the plasma radioimmunoassayed for progesterone and 13,14-dihydro-15-keto-prostaglandin F. All control ewes exhibited estrus within the expected time range and pulsatile peaks of 13,14-dihydro-15-keto-prostaglandin F occurred coincident with declining progesterone levels. With one exception, the recipient ewes had prolonged cycles and those ewes found pregnant at necropsy, 30 days after transfer, showed no progesterone decline and no pulsatile peaks of prostaglandin during days 12 to 16 after estrus. These observations suggest that the presence of the embryo at a critical stage after mating suppresses the release of uterine prostaglandin F_2α.     

Proteomic analysis of bovine conceptus fluids during early pregnancy

A proteomic analysis of bovine amniotic and allantoic fluids collected around Day 45 of gestation was performed using gel-based and LC-based MS workflows. A depletion/enrichment protocol using ultrafiltration under denaturing and reducing conditions produced an enriched fraction containing protein species predominantly between 5 and 50 kDa molecular weight. The analyses of conceptus fluid proteins were performed using two strategies; first, 2-DE coupled with MALDI-TOF-MS/MS and LC-ESI-MS/MS analysis of individual protein spots and second, a global protein snapshot of the enriched 5-50 kDa protein fraction by LC-ESI-MS/MS and LC-MALDI-TOF-MS/MS. Allocation of bovine specific protein identities was achieved by searching the Interactive Bovine In Silico SNP (IBISS) and NCBInr protein sequence databases resulting in the confident PMF identification and MS/MS confirmation of >200 2-DE generated allantoic fluids protein spots (74 individual protein species identified) and the MS/MS peptide identification of 105 LC-ESI-MS/MS generated protein identities. In total, the identity of 139 individual protein species from allantoic fluids was confirmed with peptide sequence probability MOWSE scores at the p<0.05 level or better. The comparison of bovine Day 45 amniotic and allantoic fluids protein profiles revealed differences between these two conceptus fluids in early pregnancy.     

Prostaglandin F in the fallopian tube secretion of the ewe

Oviducal secretions were obtained from conscious unrestrained ewes throughout the oestrous cycle via indwelling cannulae and the content of prostaglandin F (PGF) was determined by radioimmunoassay. Levels of PGF of up to 230 ng/ml were found in oviducal fluids obtained from ewes showing regular patterns of secretion and normal cyclical ovarian function as indicated by plasma progesterone measurement. Relatively large day to day fluctuations in content were evident, but there was no consistent relationship between concentration and stage of the oestrous cycle. Concentrations of PGF in excess of 100 ng/ml were common in preparations where autopsy later revealed infection or tissue irritation, and the concentration of PGF invariably exceeded 75 ng/ml when the concentration of protein in the oviducal fluid was abnormally high.     

Prostaglandin E2 and F2 alpha in mid-pregnant rat uterus and at parturition

Prostaglandin E2 (PGE2) and F2 alpha (PGF2 alpha) produced by 15 days pregnant rat myometrium, by parturient rat myometrium and myometrium plus endometrium were measured in vitro. The results showed that the PGs produced by parturient myometrium were higher than these obtained during mid-pregnancy. Myometrium with endometrium released more PGs than myometrium alone, and the addition of arachidonic acid (AA) at 10 DM did not show any significant effect. Exogenous progesterone or estradiol-17b at a concentration of 1 Dmol had no effect on parturient uterine PG secretions.     

Platelet-activating factor in the rabbit uterus during early pregnancy

Platelet-activating factor (PAF) concentrations were low in the non-pregnant, oestrous uterus (mean +/- s.e.m.: 2.2 +/- 1.2 pmol/g, n = 3). However, uterine PAF increased dramatically during pregnancy to a maximum of 37.8 +/- 4.90 pmol/g (n = 7) on Day 5. By Day 7, PAF concentrations in the uteri of pregnant rabbits had returned to levels similar to those found at oestrus. In contrast, uterine PAF in pseudopregnant rabbits peaked at 30.6 +/- 2.8 pmol/g (n = 8) on Day 4, declined to 20.5 +/- 2.4 pmol/g (n = 8) on Day 5 and then remained at that concentration through Day 7. Uterine PAF co-migrated with synthetic PAF (1-O-hexadecyl-2-acetyl-sn-glycero-phosphocholine) in both thin-layer and normal-phase high-performance liquid chromatography. PAF activity in the uterus during pregnancy and pseudopregnancy was found almost exclusively in the endometrium; little or no PAF was found in myometrium, uterine flushings or blastocysts. While no PAF was detected in blastocysts on Days 5 and 6 of pregnancy, the presence of the embryo appears to modulate biosynthesis and/or degradation of PAF by the uterus, since PAF decreased significantly in uterine tissue apposed to the implanting embryo (but not in similar areas between such attachment sites). Increased concentrations of PAF in the preimplantation rabbit uterus followed by a dramatic decrease on the day of blastocyst attachment suggest that this potent inflammatory autacoid may play a vital role in implantation.