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Artículos de revistas sobre el tema "Ovine pregnancy"

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Publicado: 4 de junio de 2021
Última modificación: 20 de febrero de 2023

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1

Flanagan, P. G., D. Westmoreland, N. Stallard, I. M. Stokes y J. Evans. "Ovine chlamydiosis in pregnancy". BJOG: An International Journal of Obstetrics and Gynaecology 103, n.º 4 (abril de 1996): 382–85. http://dx.doi.org/10.1111/j.1471-0528.1996.tb09749.x.

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2

Honey, Laura. "Dealing with ovine pregnancy toxaemia". In Practice 43, n.º 2 (marzo de 2021): 59. http://dx.doi.org/10.1002/inpr.14.

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3

INNES, ELISABETH A., PAUL M. BARTLEY, DAVID BUXTON y FRANK KATZER. "Ovine toxoplasmosis". Parasitology 136, n.º 14 (diciembre de 2009): 1887–94. http://dx.doi.org/10.1017/s0031182009991636.

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SUMMARYCongenital infection with Toxoplasma gondii is an important cause of abortion in sheep worldwide. The cat is the definitive host of the parasite, and infected cats may shed millions of oocysts in their faeces resulting in extensive environmental contamination and an important source of infection for grazing herbivorous animals. Studies looking at development of specific antibodies in sheep, as an indicator of exposure to T. gondii, have shown that there is an increase in seroprevalence associated with age indicating that most infections in sheep occur following birth. The stage of gestation when transplacental transmission of T. gondii to the developing foetus occurs is critical in determining the clinical outcome. The importance of endogenous transplacental transmission in persistently infected ewes and its clinical importance is a subject of current debate. Ewes infected prior to mating develop immune responses that help protect against disease in a subsequent pregnancy and also against experimental challenge administered during pregnancy. Both innate and adaptive immune responses are activated following T. gondii infection and experiments involving the chronic cannulation of peripheral lymph nodes in sheep have allowed the dynamics of the immune responses to be analysed in real time. A live vaccine, Toxovax® is the only commercially available vaccine worldwide to protect against congenital toxoplasmosis.
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4

MacLaren, LA, GB Anderson, RH BonDurant y AJ Edmondson. "Reproductive cycles and pregnancy in interspecific sheep<==>goat chimaeras". Reproduction, Fertility and Development 5, n.º 3 (1993): 261. http://dx.doi.org/10.1071/rd9930261.

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The objectives of the current study were to determine whether interspecific sheep<==>goat chimaeras exhibited reproductive cycles of their component species and were capable of maintaining ovine and caprine pregnancies to term. All chimaeras had oestrous cycles and several exhibited characteristics of both ewes and does, including short, 6-7-day cycles. Sixteen caprine pregnancies were confirmed in eight sheep<==>goat and one hybrid<==>sheep chimaera from 21 embryo transfers; of these, six appeared normal by ultrasonographic examination during Weeks 5 or 6, but none progressed beyond Week 8. Three apparent pseudopregnancies developed in two animals. In contrast, eight of 11 pregnancies in chimaeras resulted in term ovine offspring after transfer of ovine embryos or natural matings with rams. By comparison, interspecific (caprine or hybrid) pregnancies in ewes were lost in Week 4 (n = 8) or Weeks 5-6 (n = 2). First interspecific (ovine or hybrid) pregnancies in does were maintained longer (Weeks 6-12, n = 7) than second interspecific pregnancies (Weeks 4-5, n = 5) (P < 0.05) or interspecific pregnancies in ewes (P < 0.05). The results suggest that abnormal fetomaternal interactions during the early stages of implantation are responsible for termination of caprine pregnancies in the ovine or chimaeric uterus, whereas ovine conceptuses are able to implant successfully in the chimaeric uterus. All chimaeras were fertile, since each carried at least one ovine pregnancy to term following natural matings with rams.
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5

Hull, A. D., D. M. Long, L. D. Longo y W. J. Pearce. "Pregnancy-induced changes in ovine cerebral arteries". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 262, n.º 1 (1 de enero de 1992): R137—R143. http://dx.doi.org/10.1152/ajpregu.1992.262.1.r137.

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We examined the effects of pregnancy on the ovine cerebral vasculature by comparing several characteristics of isolated endothelium-intact segments of three intracranial arteries including the middle cerebral (MCA), posterior communicating (PC), and basilar (BAS) arteries taken from pregnant sheep (138-143 days gestation, term approximately 145 days) and nonpregnant controls. For comparison, segments of the extracranial common carotid (COM) artery were also studied. With pregnancy, vessel water content increased (5.4-5.8%) in all arteries except the PC. Additionally, cellular protein content increased in all arteries (4.4-50.0%). Arterial stiffness, as determined by passive stress-strain determinations, was significantly decreased during pregnancy in the MCA but not in the larger arteries. Maximum contractile responses, when normalized to vessel wall cross-sectional area, were consistently greater in arteries from pregnant than in those from nonpregnant animals (10.1-49.7%). Relaxation to the endothelium-independent guanylate cyclase stimulator S-nitroso-N-acetyl penicillamine (SNAP) increased with pregnancy only in the distal MCA (approximately 17%). Endothelium-dependent relaxation to the calcium ionophore A23187 decreased only in the larger and more proximal COM (-39%). Thus pregnancy was associated with an increase in production of contractile force, a decrease in peripheral vascular stiffness, a decrease in the relaxant response to A23187 in the COM, and an increase in the relaxant response to SNAP in the MCA. Together, these findings indicate that pregnancy has widespread and important vessel specific cerebrovascular consequences that affect not only arterial composition, but also contractility and endothelial reactivity.
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6

Keller-Wood, Maureen. "ACTH responses to CRF and AVP in pregnant and nonpregnant ewes". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 274, n.º 6 (1 de junio de 1998): R1762—R1768. http://dx.doi.org/10.1152/ajpregu.1998.274.6.r1762.

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During both ovine and human pregnancy plasma cortisol is increased. In human pregnancy the placenta secretes corticotropin-releasing factor (CRF), but pituitary responses to CRF are decreased. However, in ovine pregnancy there is no measurable placental secretion of CRF. This study tests for changes in pituitary responsiveness to CRF or AVP. Pregnant and nonpregnant ewes were infused with saline or CRF at three doses (3, 9, 45 μg/h), with or without coinfusion of AVP (9 μg/h). AVP infusion increased plasma AVP to ∼250 pg/ml. CRF infusions increased plasma CRF from ∼25 to 50, 150, and 850 pg/ml. ACTH was significantly increased by the infusion of AVP and by all infusions of CRF. Within-animal comparisons revealed a potentiation of the ACTH response to CRF in the presence of AVP. The ACTH responses to AVP and/or CRF were not different between pregnant and nonpregnant ewes. The results suggest that there is no change in pituitary responsiveness to CRF or AVP during ovine pregnancy.
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7

Simmons, Rebecca M., David W. Erikson, Jinyoung Kim, Robert C. Burghardt, Fuller W. Bazer, Greg A. Johnson y Thomas E. Spencer. "Insulin-Like Growth Factor Binding Protein-1 in the Ruminant Uterus: Potential Endometrial Marker and Regulator of Conceptus Elongation". Endocrinology 150, n.º 9 (4 de junio de 2009): 4295–305. http://dx.doi.org/10.1210/en.2009-0060.

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Abstract Establishment of pregnancy in ruminants requires conceptus elongation and production of interferon-τ (IFNT), the pregnancy recognition signal that maintains ovarian progesterone (P4) production. These studies determined temporal and spatial alterations in IGF binding protein (IGFBP)-1 and IGFBP3 in the ovine and bovine uterus; effects of P4 and IFNT on their expression in the ovine uterus; and effects of IGFBP1 on ovine trophectoderm cell proliferation, migration, and attachment. IGFBP1 and IGFBP3 were studied because they are the only IGFBPs specifically expressed by the endometrial luminal epithelia in sheep. In sheep, IGFBP1 and IGFBP3 expression was coordinate with the period of conceptus elongation, whereas only IGFBP1 expression was coordinate with conceptus elongation in cattle. IGFBP1 mRNA in the ovine endometria was between 5- and 29-fold more abundant between d 12 and 16 of pregnancy compared with the estrous cycle and greater on d 16 of pregnancy than nonpregnancy in the bovine uterus. In sheep, P4 induced and IFNT stimulated expression of IGFBP1 but not IGFBP3; however, the effect of IFNT did not mimic the abundant increase observed in pregnant ewes. Therefore, IGFBP1 expression in the endometrium is regulated by another factor from the conceptus. IGFBP1 did not affect the proliferation of ovine trophectoderm cells in vitro but did stimulate their migration and mediate their attachment. These studies reveal that IGFBP1 is a common endometrial marker of conceptus elongation in sheep and cattle and most likely regulates conceptus elongation by stimulating migration and attachment of the trophectoderm.
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8

Santos, A. C., G. R. Arthur, H. Pedersen, H. O. Morishima, M. Finster y B. G. Covino. "Systemic Toxicity of Ropivacaine during Ovine Pregnancy". Anesthesiology 75, n.º 1 (1 de julio de 1991): 137–41. http://dx.doi.org/10.1097/00000542-199107000-00022.

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9

Zoli, A. P., J. F. Beckers y F. Ectors. "Isolation of an ovine pregnancy specific protein". Theriogenology 33, n.º 1 (enero de 1990): 366. http://dx.doi.org/10.1016/0093-691x(90)90790-z.

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10

Magness, R. R., M. D. Mitchell y C. R. Rosenfeld. "Uteroplacental production of eicosanoids in ovine pregnancy". Prostaglandins 39, n.º 1 (enero de 1990): 75–88. http://dx.doi.org/10.1016/0090-6980(90)90096-e.

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11

Guo, Yanhua, Jiachen Bai, Zhenliang Zhang, Yucheng Liu, Shouliang Lu, Changbin Liu, Jianhong Ni et al. "Pregnancy of Cryopreserved Ovine Embryos at Different Developmental Stages". Cryoletters 43, n.º 5 (1 de septiembre de 2022): 269–75. http://dx.doi.org/10.54680/fr22510110512.

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BACKGROUND: Developmental stage and cryopreservation method have significant impact on the pregnancy rate after transfer of embryos produced in vivo. OBJECTIVE: To determine the pregnancy outcomes from ovine embryos cryopreserved at different developmental stages. MATERIALS AND METHODS: Embryos at different developmental stages were obtained from donor ewes through simultaneous estrus treatment and laparoscopic artificial insemination. Embryos, either cryopreserved via vitrification or slow freezing method, were implanted into recipient ewes. The pregnancy rate was determined 35 days after transfer. RESULTS: The pregnancy rate of developing embryos increases after transfer from the morula stage, early blastocyst to expanded blastocyst stages (64.9%, 73.9% and 81.3%, respectively). However, cryopreservation significantly decreases the pregnancy rate of embryos at all three developmental stages, and there is no significant difference among developmental stages (43.9%, 43.7%, 52.9%, respectively). There is also no significant difference in the pregnancy rate between slowly-frozen embryos and vitrified embryos. CONCLUSION: The pregnancy outcomes of embryo transfer is better at the expanded blastocyst stage than at earlier stages. However, no difference is observed in the pregnancy rate of embryos at different developmental stage after cryopreservation, either by slow freezing and vitrification. Cryopreservation methods for ovine embryos, both slow freezing and vitrification, need further improvement.
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12

Tekin, Şaban y Peter J. Hansen. "Natural Killer-Like Cells in the Sheep: Functional Characterization and Regulation by Pregnancy-Associated Proteins". Experimental Biology and Medicine 227, n.º 9 (octubre de 2002): 803–11. http://dx.doi.org/10.1177/153537020222700913.

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Natural killer (NK) cells represent an important component of the innate immune system. In ruminants there are few reports regarding presence or characterization of NK cells. Although absence of expression of major histocompatibility complex proteins on ovine trophoblast makes it potentially a target for NK cells, little is known about regulation of NK cells by products of pregnancy in sheep. Objectives of the present study were to determine whether cells with characteristics of NK cells exist in preparations of ovine peripheral blood lymphocytes (PBL) and endometrial epithelial cells (EEC) and to determine regulation of such cells by two pregnancy-associated molecules with immunoregulatory properties (ovine uterine serpin [OvUS] and interferon-τ [IFN-τ]). Ovine PBL and EEC lysed a putative NK target cell, the BHV-1 infected D17 cell, and lysis by both types of cells was neutralized by antibody against a molecule called function-associated molecule (FAM) expressed on NK cells of several species. Moreover, inhibitors that interfere with perforin-mediated lysis blocked NK-like activity of PBL. The NK-like lytic activity of PBL and EEC was inhibited by OvUS, whereas ovine and bovine IFN-τ significantly enhanced NK-like activity of PBL. In conclusion, NK-like activity present in preparations of ovine PBL and EEC is mediated by FAM+ cells, is dependent on processes that involve perforin processing, and is regulated by OvUS and IFN-τ. Inhibition of NK-like activity of PBL and EEC by OvUS is consistent with a role for OvUS in protecting the conceptus from maternal cytotoxic lymphocytes. Stimulation of lysis by IFN-τ implies the existence of other inhibitory mechanisms during early pregnancy to prevent NK cell-mediated destruction of the conceptus.
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13

Spencer, TE, GH Graf y FW Bazer. "Sulfated glycoprotein-1 (SGP-1) expression in ovine endometrium during the oestrous cycle and early pregnancy". Reproduction, Fertility and Development 7, n.º 5 (1995): 1053. http://dx.doi.org/10.1071/rd9951053.

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This study determined effects of day of oestrous cycle and early pregnancy on sulfated glycoprotein-1 (SGP-1) expression in ovine endometrium. A 364-bp clone of the ovine SGP-1 mRNA was amplified from reverse transcribed Day-15 cyclic endometrial mRNA using the polymerase chain reaction (PCR) and primers specific for the rat SGP-1 mRNA sequence. Nucleotide sequence of the ovine SGP-1 cDNA shared significant identity with rat SGP-1 and human prosaposin. Ewes (n = 40) were hysterectomized on either Day 1, 6, 11, 13 or 15 of the oestrous cycle or on Day 11, 13, 15, 17 or 25 of early pregnancy. Total cellular RNA was isolated from endometrium and subjected to Northern and slot blot hybridization analyses using an antisense cRNA probe transcribed from the ovine SGP-1 cDNA clone. A single 2.6-kb mRNA transcript was detected by Northern hybridization analyses. Slot blot hybridization analyses indicated that steady-state levels of endometrial SGP-1 mRNA varied during the oestrous cycle (cubic, P < 0.02) and increased between Day 11 and Day 25 of early pregnancy (linear, P < 0.01). On Days 11, 13 and 15, endometrial SGP-1 mRNA levels were greater in pregnant ewes than in cyclic ewes (day x pregnancy status, P < 0.01). Immunohistochemical localization of SGP-1 in uterine tissues with rabbit anti-rat SGP-1 antibody revealed intense immunoreactivity associated primarily with the endometrial epithelium. These results indicate that the ovine endometrium expresses SGP-1, a prosaposin, and that SGP-1 expression varies during the oestrous cycle and is enhanced by the conceptus. The presence of SGP-1 in the endometrium suggests intracellular and extracellular roles for this protein in glycosphingolipid metabolism or transport in the uterine environment.
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14

Kelly, J., D. Kleemann, M. Kuwayama y S. Walker. "88 PREGNANCY RATES FOR IN VITRO AND IN VIVO PRODUCED OVINE EMBRYOS VITRIFIED USING THE MINIMUM VOLUME COOLING CRYOTOP METHOD". Reproduction, Fertility and Development 17, n.º 2 (2005): 194. http://dx.doi.org/10.1071/rdv17n2ab88.

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Previously we reported that, using the minimum volume cooling (MVC) cryotop vitrification method, in vitro-produced ovine and bovine embryo survival after thawing was similiar to that of fresh embryos (Kelly et al. 2004 Reprod. Fert. Dev. 16, 172). While survival of vitrified embryos after thawing can be indicative of embryo viability, this assessment does not always correlate with embryo survival after transfer. This study assesses the effect of vitrification using the MVC cryotop method on the survival after transfer of in vitro- and in vivo-produced ovine embryos. Fresh or vitrified Day 6 ovine embryos (expanded blastocysts, blastocysts, compact morulae) were used in this study. Ovine cumulus–oocyte complexes were obtained and matured, fertilized (Day 0), and cultured in vitro (Walker et al. 1996 Biol. Reprod. 55, 703–708). In vitro embryos for vitrification were produced and vitrified (Kelly et al. 2004 Reprod. Fert. Dev. 16, 172) 10 days prior to the day of transfer. In vivo embryos were recovered from donor Merino ewes and vitrified 7 days prior to the day of transfer while fresh in vivo embryos were collected and transferred on the same day. Semen used for both in vivo and in vitro embryo production was from the same sire. On the day of transfer, vitrified embryos were thawed directly into 1.25 M sucrose solution, followed by stepwise dilution of the cryoprotectants. Embryos were transferred as singles into synchronized recipient ewes on a randomized basis. Fetal number was detected at Day 50. Variables were assessed using the CATMOD procedure in SAS. Pregnancy rate for in vivo-derived embryos was higher (P < 0.01) than for in vitro-derived embryos. Embryo treatment (fresh vs. vitrified) did not significantly affect pregnancy rate. Pregnancy rate for ewes detected (by vasectomized rams) in estrus within 48 h of progesterone pessary removal was higher (P < 0.05) than for both the 48–68 h and unmarked groups. The latter two groups did not differ significantly. None of the first-order interactions were significant (P > 0.05). This study demonstrates that ovine embryos (in vitro and in vivo) can be vitrified, thawed, and transferred without compromising embryo viability. However, the differences in pregnancy rate between the recipient groups warrant further investigation. The MVC cryotop method is a vitrification technique that can be adapted to routine field use. Table 1. Pregnancy rate of fresh and vitrified in vivo and in vitro ovine embryos after embryo transfer
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15

Annibale, D. J., C. R. Rosenfeld, J. T. Stull y K. E. Kamm. "Protein content and myosin light chain phosphorylation in uterine arteries during pregnancy". American Journal of Physiology-Cell Physiology 259, n.º 3 (1 de septiembre de 1990): C484—C489. http://dx.doi.org/10.1152/ajpcell.1990.259.3.c484.

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During pregnancy, the ovine uterine artery changes from a low- to a high-stress artery. We investigated the hypotheses that the increased stress reflects alterations in vessel wall cellularity, smooth muscle cell contractile protein contents, or activation properties. Uterine artery diameter increased during pregnancy, whereas the fractional cellular composition and thickness of the muscularis were unchanged. Results of morphometry suggest that vessel growth is associated with cell elongation. Uterine arteries from pregnant ewes had greater protein contents than those from nonpregnant ewes (104 vs. 69 mg/g, respectively); there were corresponding increases in the absolute cellular contents of actin and myosin. While the fraction of light chain phosphorylated in response to phenylephrine was unaltered, the total amount of myosin light chain phosphorylated per gram wet weight increased significantly during pregnancy. In addition, the distribution of myosin heavy chain isoforms was also altered during pregnancy. The increased stress observed in the uterine artery during ovine pregnancy reflects, in part, increases in cellular contractile protein concentrations associated with hypertrophy.
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16

Parkinson, T. J., H. J. Stewart, M. G. Hunter, D. S. C. Jones, D. C. Wathes y A. P. F. Flint. "Evidence against a role for blastocyst-secreted oxytocin in early pregnancy maintenance in sheep". Journal of Endocrinology 130, n.º 3 (septiembre de 1991): 443—NP. http://dx.doi.org/10.1677/joe.0.1300443.

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ABSTRACT Analysis of ovine conceptus RNA by slot blotting, Northern analysis and nested polymerase chain reaction failed to detect oxytocin–neurophysin prohormone mRNA. Probes used hybridized with both the 3' end of the prohormone mRNA and the oxytocin-coding sequence. Northern analysis of bovine and porcine conceptus RNA was also negative, and polymerase chain reaction demonstrated oxytocin–neurophysin mRNA in ovine corpus luteum, but not in human corpus luteum or decidua, or in ovine endometrium. Infusion of oxytocin into the uterine lumen in cyclic ewes between days 9 and 19 or 20 after oestrus failed to prolong the luteal phase of the cycle and had no effect on endometrial oxytocin receptor concentrations or uterine prostaglandin F secretion. Oxytocin administered systematically prevented luteolysis and reduced uterine prostaglandin F secretion. Taken together, these data suggest that blastocyst-derived oxytocin is unlikely to contribute to corpus luteum maintenance in early pregnancy. They are inconsistent with a previous report that the ovine blastocyst synthesizes and secretes oxytocin. Journal of Endocrinology (1991) 130, 443–449
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17

Cha, Sang C., Graham W. Aberdeen, Suhayla Mukaddam-Daher, Edmond W. Quillen y Bahij S. Nuwayhid. "Autoregulation of Renal Blood Flow During Ovine Pregnancy". Hypertension in Pregnancy 12, n.º 1 (enero de 1993): 71–83. http://dx.doi.org/10.3109/10641959309031054.

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18

Lacroix, M. C., G. Charpigny y P. Reinaud. "IS OXYTOCIN OF CONCEPTUS ORIGIN INVOLVED IN INHIBITION OF LUTEAL REGRESSION IN EARLY PREGNANCY IN EWES?" Journal of Endocrinology 118, n.º 3 (septiembre de 1988): R17—R20. http://dx.doi.org/10.1677/joe.0.118r017.

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ABSTRACT This study describes the presence in and production by the ovine conceptus of an oxytocin-like peptide during the early stages of development. Oxycotin was measured by radioimmunoassay in ovine conceptuses from days 14 to 30 of pregnancy. Tissue concentrations of oxytocin increased from day 14 (24.8 ± 5 pg/100 mg) until day 19 (122.9 ± 52 pg/100 mg) and then decreased (3 ± 1 pg /100 mg). Oxytocin was released into culture medium by day-15 ovine conceptuses at a rate of 262 ± 55 pg/24 h. Reverse-phase high-performance liquid chromatography (HPLC) analysis of peptides extracted from a pool of ovine conceptuses was conducted using chromatographic conditions developed to separate oxytocin from other nonapeptides. Radioimmunoassay of HPLC fractions for oxytocin revealed an immunoactive conceptus peptide in a single fraction at the same retention time as chromatographed authentic oxytocin. Radioimmunoassay and chromatographic data therefore suggest that this oxytocin-like peptide is similar, if not identical, to authentic oxytocin. Concentrations of oxytocin in conceptus tissue were maximal during the period of inhibition of luteal regression (days 14-19). It is proposed that conceptus oxytocin is involved in the maintenance of luteal function in early pregnancy.
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19

Charles, David. "How to: ovine clinical examination". Livestock 28, n.º 1 (2 de enero de 2023): 41–49. http://dx.doi.org/10.12968/live.2023.28.1.41.

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When asked to consider the core activities of a large animal practitioner, many would conjure up images of vets standing at the back end of a cow performing rectal palpation, or ultrasound for pregnancy diagnosis. However, the essential skill in any large animal practitioner's toolbox is the ability to perform a thorough and accurate clinical examination. This article discusses approaches to the ovine clinical examination, the nuances and differences expected for rams and neonates.
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20

Arikan, Ş. y A. A. Yigit. "Size distribution of steroidogenic and non-steroidogenic ovine luteal cells throughout pregnancy". Animal Science 75, n.º 3 (diciembre de 2002): 427–32. http://dx.doi.org/10.1017/s1357729800053194.

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AbstractThe present study examines the size distribution of ovine steroidogenic and non-steroidogenic luteal cells throughout pregnancy. Cells were isolated from corpora lutea collected from early (< 8 weeks), mid (9 to 14 weeks) or late (15 to 18 weeks) stages of pregnancy. Cells were stained for 3β-hydroxysteroid dehydrogenase (3β-HSD) activity, a marker for steroidogenic cells. Both 3β-HSD positive and β-HSD negative cells covered a wide spectrum of size ranging from 7 to 37 μm in diameter. There was a significant increase (P > 0·01) in mean diameter of non-steroidogenic luteal cells as pregnancy progressed. Mean diameter of 3β-HSD negative cells increased from 17·8 (s.e. 0·4) μm in the corpus luteum of early stage of pregnancy to 22·4 (s.e. 0·3) μm in the corpus luteum of advanced pregnancy. However, there was no significant increase in the mean diameter of 3β-HSD positive cells. Corpora lutea obtained from early stages of the pregnancy contained more steroidogenic cells than the cells obtained from mid and late pregnancy (P < 0·01). Percentage of 3β-HSD negative cells had increased 2·07-fold by 18 weeks of pregnancy when compared with the early stage of pregnancy. In contrast, percentage of 3β-HSD positive cells had decreased to 50% of starting values during the same period (P < 0·05). These results indicate that the ovine corpus luteum of pregnancy is morphologically dynamic over the course of pregnancy. Steroidogenic activity of luteal cells may decrease as pregnancy progresses, especially activity of the large luteal cells.
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Kiyma, Z., M. Hitit, C. Ozel, G. Sen, M. Kose, A. Guzeloglu, M. Kaya et al. "121 EXPRESSION OF HYALURONAN SYSTEM COMPONENTS IN THE EARLY PREGNANT OVINE ENDOMETRIUM". Reproduction, Fertility and Development 27, n.º 1 (2015): 152. http://dx.doi.org/10.1071/rdv27n1ab121.

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Hyaluronan (HA; hyaluronic acid), a member of glycosaminoglycans (GAG) family, is the main polysaccharide and is expressed in almost all tissues including those of the reproductive tract. Three different hyaluronic acid-synthase (HAS) enzymes, HAS1, HAS2, and HAS3, synthesise HA. The action of HA depends on its molecular size and its cell surface receptor (CD44). Hyaluronidases (HYAL) are a group of enzymes, HYAL-1 and HYAL-2, that degrade HA. Roles of the HA system in reproductive events include oocyte maturation, fertilization, and implantation. It is also known that ovarian steroids, specifically progesterone, regulate the HA system in the endometrium. Moreover, HA-mediated cell signalling participates in embryonic development. The aim of this study was to evaluate expression of the HA system at the mRNA level in the early pregnant ovine endometrium at pre-implantation stage. Therefore, endometrial tissue samples were collected on Day 13 of the oestrous cycle (n = 10) and pregnancy (n = 14). Relative mRNA expression levels of HA system genes were quantified using quantitative RT-qPCR. Data were analysed using one-way ANOVA and l.s.d. test. All of the studied components of the HA system (HAS1, HAS2, HAS3, HYAL1, HYAL2, and CD44) were expressed in the ovine endometrium. Steady-state mRNA levels of HAS1, HYAL1, HYAL2, and CD44 were not significantly different between cyclic and early pregnant ovine endometrium on Day 13. However, expression of HAS2 and HAS3 appeared to be down-regulated in early pregnancy. Considering that both cyclic and pregnant endometrium on Day 13 is under the influence of progesterone, detected differential regulation of some components of HA system in the ovine endometrium may be directly related to the effects of the presence of an embryo. The role of the HA system in ovine endometrium at later stages of pregnancy warrants further investigation. Partially funded by TUBITAK-112R022 to ZK and SUBAP to AG.
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22

Keller-Wood, M. "Corticotropin responses to hypoglycemia and hypotension during ovine pregnancy". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 266, n.º 1 (1 de enero de 1994): R180—R187. http://dx.doi.org/10.1152/ajpregu.1994.266.1.r180.

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The adrenocorticotropic hormone (ACTH) responses to hypoglycemia and to hypotension were compared in pregnant and nonpregnant ewes. In the first study pregnant and nonpregnant ewes were each subjected to hypoglycemia induced by injection of 0.05, 0.10, or 0.25 U regular insulin/kg body wt or to saline infused as a control. In the second study pregnant and nonpregnant ewes were subjected to hypotension induced by the infusion of 2.5, 5.0, or 10.0 micrograms nitroprusside.kg-1.min-1 or to dextrose infused as a control. ACTH responses to hypoglycemia were significantly increased in the pregnant ewes, and the relation between plasma glucose and plasma ACTH was shifted to the right, indicating greater ACTH responses for a given level of hypoglycemia in the pregnant state. The mean ACTH response to infusion of nitroprusside was reduced during pregnancy, despite significantly lower mean arterial blood pressure in the pregnant ewes. When the relation between mean arterial pressure and ACTH was compared in the two groups of ewes, the relation was significantly shifted to the left in the pregnant ewes, indicating lower ACTH responses to a given level of pressure during pregnancy. The results suggest that pregnancy does not uniformly alter ACTH responses to stimuli, suggesting multiple, stimulus-specific effects of pregnancy on the hypothalamo-pituitary-adrenal axis.
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23

Milisits-Németh, Tímea, Orsolya Gabriella Balogh, István Egerszegi, László Kern, R. Garth Sasser y György Gábor. "Detection of pregnancy in sheep using an ELISA for pregnancy-specific protein B". Acta Veterinaria Hungarica 66, n.º 2 (junio de 2018): 329–36. http://dx.doi.org/10.1556/004.2018.029.

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The early detection of pregnancy and the determination of fetal numbers have economic benefits in sheep production because of the seasonal breeding patterns where missing a breeding opportunity means the loss of one productive year. The purpose of this study was to evaluate the efficacy of the B6-HRP ELISA for ovine pregnancy-specific protein B (oPSPB) measurement in the detection of pregnancy and estimation of fetal numbers in different sheep breeds. BioPRYN® ELISA assay kit was used for the detection of pregnancy in the experimental animals. Ninety-three ewes of three breeds (British Milksheep – BM, Lacaune – L and Transylvanian Racka – TR), each from three farms in Hungary, were included in the study. BM and L ewes were artificially inseminated (AI). Thirty-five days after AI, all ewes were examined by transabdominal ultrasound. The TR flock was mated naturally over a six-week period. At the end of the mating period, the ewes were similarly examined by ultrasound. Blood samples were taken from all pregnant ewes twice (35 and 65 days after AI), and serum samples were assayed by the BioPRYN test. It can be concluded that the detection of serum PSPB by ELISA is a much easier, safer, less expensive and highly accurate method for the detection of ovine pregnancy. Although some breed-related differences were detectable at 35 and 65 days post breeding, no differences in oPSPB levels were found in pregnant ewes carrying different numbers of fetuses.
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24

Keller-Wood, M. "Vasopressin response to hyperosmolality and hypotension during ovine pregnancy". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 266, n.º 1 (1 de enero de 1994): R188—R193. http://dx.doi.org/10.1152/ajpregu.1994.266.1.r188.

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The arginine vasopressin (AVP) responses to hyperosmolality and to hypotension were compared in pregnant and nonpregnant ewes. When the responses to infusion of normal or hypertonic saline were compared, plasma AVP and Na+ concentrations were lower in pregnant ewes than nonpregnant ewes, but the relation between plasma AVP and Na+ concentrations was not altered in the pregnant state. In a second study the AVP response to hypotension, induced by the infusion of 2.5, 5.0, or 10.0 micrograms nitroprusside.kg-1.min-1, was compared in pregnant and nonpregnant ewes. Despite significantly lower mean arterial blood pressures in the pregnant ewes, the mean plasma AVP concentration after infusion of nitroprusside was not increased during pregnancy. Therefore, the relation between mean arterial pressure and AVP was significantly shifted to the left in the pregnant ewes, indicating lower AVP concentrations for a given level of arterial pressure during pregnancy. The results suggest that pregnancy alters the regulation of AVP by arterial pressure but does not affect the regulation of AVP by plasma sodium concentration in the ewe.
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25

Yang, Ling, Xu Han, Leying Zhang, Ning Li, Zimo Zhao y Jiachen Bai. "Changes in expression of prostaglandin synthase in ovine liver during early pregnancy". Canadian Journal of Animal Science 100, n.º 3 (1 de septiembre de 2020): 432–39. http://dx.doi.org/10.1139/cjas-2019-0171.

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Liver can function as part of the innate and adaptive immune systems. We hypothesize that prostaglandins participate in the regulation of hepatic immune function during early pregnancy in sheep. The objective of this study was to elucidate expression of prostaglandin synthase in ovine liver during early pregnancy. Ovine livers were sampled on day 16 of the estrous cycle, and days 13, 16, and 25 of pregnancy, and the expression of prostaglandin synthases, including prostaglandin-endoperoxide synthase 1 (PTGS1), PTGS2, prostaglandin E synthase (PTGES), and aldo-keto reductase family 1, member B1, a prostaglandin F synthase (PGFS), were detected by quantitative real-time polymerase chain reaction, Western blot, and immunohistochemistry analysis. There were increases in the expression of mRNA and the proteins of PTGS2, PTGES, and PGFS in the livers during early pregnancy, but PTGS1 was decreased in the pregnant ewes. The PGFS protein was limited to the hepatocytes and the endothelial cells of the proper hepatic arteries and hepatic portal veins. In summary, the upregulation of PTGS2, PTGES, and PGFS and downregulation of PTGS1 may be involved in the maternal hepatic immune adjustment during early pregnancy in sheep.
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26

Soares, MC, JL Servely, C. Puissant, P. Bolifraud, MC Lacroix, B. Schaeffer y G. Kann. "Ovine chorionic somatomammotrophin (oCS) production by isolated cotyledon cells from sheep in early and mid gestation: auto-regulation by recombinant oCS". Journal of Endocrinology 161, n.º 2 (1 de mayo de 1999): 289–98. http://dx.doi.org/10.1677/joe.0.1610289.

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We report the ability of sheep placental cotyledonary cells, isolated at different periods of pregnancy (40 to 90 days) to produce ovine chorionic somatomammotrophin (oCS) in in vitro culture conditions. This oCS production increased gradually with stage of pregnancy. Endogenous oCS net production by isolated placental cells was increased, in a dose-dependent manner, by addition of recombinant oCS (roCS). This effect was not observed after addition of recombinant ovine growth hormone. The roCS effect was more potent on cells collected during early pregnancy. Specific immunoprecipitation of oCS revealed that roCS treatment was associated with an increased dose-dependent incorporation of [35S]methionine-[35S]cysteine. These findings provide evidence that oCS may act in a paracrine/autocrine manner to up-regulate its own production during early gestation. We suggest that this autoregulation may be associated with morphological and functional differentiation of the trophoblast during the growth of the placenta.
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27

Annibale, D. J., C. R. Rosenfeld y K. E. Kamm. "Alterations in vascular smooth muscle contractility during ovine pregnancy". American Journal of Physiology-Heart and Circulatory Physiology 256, n.º 5 (1 de mayo de 1989): H1282—H1288. http://dx.doi.org/10.1152/ajpheart.1989.256.5.h1282.

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During pregnancy, sheep develop attenuated systemic and uterine vascular responsiveness to alpha-adrenergic stimulation. To determine whether this reflects altered vascular smooth muscle function, we studied the responsiveness of smooth muscle isolated from systemic and uterine arteries to KCl and phenylephrine. Uterine, renal, and carotid arteries were collected from nonpregnant, pregnant (131 +/- 2 days, +/- SD), and late postpartum (144 +/- 4 days) ewes; endothelium was removed and open rings were hung for measurement of isometric force. There were no differences in concentration-response relationships nor maximal stresses generated to phenylephrine between nonpregnant, pregnant, and late postpartum states for carotid or renal arteries. However, the 50% maximal concentration for phenylephrine of uterine arteries in the nonpregnant state (2.8 +/- 0.9 x 10(-6) M) was greater than the pregnant state (0.76 +/- 0.05 x 10(-6) M). Moreover, uterine arteries from pregnant sheep generated significantly more stress than those from nonpregnant sheep (2.2 +/- 0.23 vs. 0.73 +/- 0.23 x 10(6) dyn/cm2, P less than 0.01). The attenuated systemic and uterine vascular responses associated with pregnancy do not result from diminished adrenergic sensitivity or contractile capability of arterial smooth muscle. In contrast, there is increased stress-generating capacity of uterine arterial smooth muscle during pregnancy, which is reversed during the postpartum period.
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28

El Amiri, B., A. Karen, J. Sulon, N. Melo de Sousa, AV Alvarez-Oxiley, Y. Cognié, O. Szenci y JF Beckers. "Measurement of Ovine Pregnancy-Associated Glycoprotein (PAG) During Early Pregnancy in Lacaune Sheep". Reproduction in Domestic Animals 42, n.º 3 (junio de 2007): 257–62. http://dx.doi.org/10.1111/j.1439-0531.2006.00761.x.

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29

Sandra, Olivier, Isabelle Bataillon, Pascale Roux, Jacques Martal, Gilles Charpigny, Pierrette Reinaud, Philippe Bolifraud, Guy Germain y Kaïs H. Al-Gubory. "Suppressor of cytokine signalling (SOCS) genes are expressed in the endometrium and regulated by conceptus signals during early pregnancy in the ewe". Journal of Molecular Endocrinology 34, n.º 3 (junio de 2005): 637–44. http://dx.doi.org/10.1677/jme.1.01667.

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It is established that the conceptus–endometrium dialogue involves cytokines, growth factors and hormones. Given the crucial functions of the suppressor of cytokine signaling (SOCS) family proteins in cytokine signalling, we analyzed the expression and the regulation of CIS and SOCSs 1–3 transcripts during early pregnancy in the ovine endometrium. An overall stimulation of the SOCS transcripts was described in the pregnant ewes with two specific patterns. Unilaterally pregnant ewes confirmed the conceptus-produced factors as regulators of the SOCSs 1–3 expression at day 16 of pregnancy. Intrauterine injection of recombinant ovine interferon τ (IFNτ) in cyclic ewes stimulated the expression of the SOCS mRNA with various potencies, therefore suggesting that the SOCS could take part in the negative regulation of the IFNτ signalling pathway.
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30

Philipps, A. F., T. S. Rosenkrantz y J. Raye. "Consequences of Perturbations of Fetal Fuels in Ovine Pregnancy". Diabetes 34, Supplement_2 (1 de junio de 1985): 32–35. http://dx.doi.org/10.2337/diab.34.2.s32.

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31

Mukaddam-Daher, S., J. Gutkowska, B. S. Nuwayhid y E. W. Quillen. "Metabolic clearance of atrial natriuretic factor in ovine pregnancy". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 267, n.º 5 (1 de noviembre de 1994): R1413—R1420. http://dx.doi.org/10.1152/ajpregu.1994.267.5.r1413.

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Plasma atrial natriuretic factor (ANF) is normally released into the circulation primarily by volume expansion and atrial distension, but we have shown that plasma ANF is elevated in pregnant sheep before volume expansion. Because alterations in the metabolic clearance of ANF could lead to elevated plasma ANF levels, the present study was designed to determine the pharmacokinetics of plasma ANF in pregnant sheep. Chronically instrumented nonpregnant and pregnant sheep received intravenous injections of monoiodinated human ANF (125I-hANF). Plasma decay curves of 125I-hANF followed a biexponential function in both groups. High-performance liquid chromatography (HPLC) revealed the accumulation of smaller degradation products by 2 min postinjection, and by 30 min no intact ANF was present. Because HPLC identification of ANF and its metabolites was shown to be more efficient than precipitation with 10% trichloroacetic acid (TCA) or extraction by Sep-Pak cartridges, ANF kinetic parameters were calculated from HPLC-corrected plasma decay curves. Injected ANF was rapidly distributed in an initial distribution volume (IDV) that was expanded in pregnant sheep. Metabolic clearance rate (MCR) was greater in pregnant sheep (2.8 +/- 0.3 vs. 6.8 +/- 1.2 l/min, P = 0.002), while plasma half-life (t1/2) was not altered (2.2 +/- 0.5 vs. 2.4 +/- 0.4 min). The data demonstrate that during pregnancy, the t1/2 of ANF is not altered but the MCR of ANF is enhanced. These findings imply that plasma ANF is increased by mechanisms other than reduced clearance in pregnant sheep.
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32

Cha, S. C., G. W. Aberdeen, S. Mukaddam-Daher, E. W. Quillen y B. S. Nuwayhid. "Tubular handling of fluid and electrolytes during ovine pregnancy". American Journal of Physiology-Renal Physiology 265, n.º 2 (1 de agosto de 1993): F278—F284. http://dx.doi.org/10.1152/ajprenal.1993.265.2.f278.

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Pregnancy is characterized by progressive water and sodium accumulation and increases in renal blood flow (RBF) and glomerular filtration rate (GFR). However, the influence of the different nephron segments on the increased tubular reabsorption is controversial. Consequently, four nonpregnant and five pregnant sheep were studied, after chronic instrumentation, to assess salt and water reabsorption in the proximal and distal tubules under basal and volume-loaded conditions. Lithium clearance was used as a marker for proximal tubular reabsorption. Volume loading was achieved by the rapid administration of 1,000 ml isotonic saline followed by 250 ml/h for 2 h. Under basal conditions with reference to the nonpregnant state, pregnant sheep had higher (P < 0.05) levels of right RBF (427 +/- 34 vs. 313 +/- 8 ml/min), GFR (133 +/- 7 vs. 94 +/- 9 ml/min), proximal tubular reabsorption (102 +/- 7 vs. 73 +/- 6 ml/min), distal nephron fluid delivery (31 +/- 2 vs. 20 +/- 2 ml/min), and fractional distal nephron reabsorption of fluid (92 +/- 2 vs. 87 +/- 1%) and sodium (98.8 +/- 0.3 vs. 97.0 +/- 0.7%). However, pregnant animals had significantly (P < 0.05) reduced fractional excretions of fluid (1.6 +/- 0.3 vs. 2.6 +/- 0.2%) and sodium (0.24 +/- 0.06 vs. 0.63 +/- 0.19%), but similar levels of filtration fraction, fractional proximal tubular reabsorption, urine flow, urinary sodium excretion, and osmolar and free water clearance. After saline loading, pregnant sheep excreted significantly (P < 0.05) less sodium (9.2 vs. 28.6%) and water (39.8 vs. 56.5%). Decreases in fractional proximal and distal nephron reabsorption of sodium and water after saline loading were attenuated in pregnant animals.(ABSTRACT TRUNCATED AT 250 WORDS)
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33

Janowiak, Mary A., Ronald R. Magness, Deirdre A. Habermehl y Ian M. Bird. "Pregnancy Increases Ovine Uterine Artery Endothelial Cyclooxygenase-1 Expression*". Endocrinology 139, n.º 2 (1 de febrero de 1998): 765–71. http://dx.doi.org/10.1210/endo.139.2.5739.

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34

MITCHELL, G. M. y B. F. STRATFORD. "The morphology of the ovine placenta in pregnancy toxaemia". Australian Veterinary Journal 64, n.º 7 (julio de 1987): 221–23. http://dx.doi.org/10.1111/j.1751-0813.1987.tb15189.x.

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35

Curry, Steven C., G. Randall Bond, Robert Raschke, David Tellez y Donna Wiggins. "An ovine model of maternal iron poisoning in pregnancy". Annals of Emergency Medicine 19, n.º 6 (junio de 1990): 632–38. http://dx.doi.org/10.1016/s0196-0644(05)82466-7.

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36

Cox, B. E., M. A. Ipson, P. W. Shaul, K. E. Kamm y C. R. Rosenfeld. "Myometrial angiotensin II receptor subtypes change during ovine pregnancy." Journal of Clinical Investigation 92, n.º 5 (1 de noviembre de 1993): 2240–48. http://dx.doi.org/10.1172/jci116827.

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37

Lacroix, MC, H. Jammes y G. Kann. "Occurrence of a growth hormone-releasing hormone-like messenger ribonucleic acid and immunoreactive peptide in the sheep placenta". Reproduction, Fertility and Development 8, n.º 3 (1996): 449. http://dx.doi.org/10.1071/rd9960449.

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Growth hormone releasing factor (GHRH) has been described in the rat, mouse and human placentae. This study reports the presence of an immunoreactive GHRH activity (IR-GHRH) in the ovine placenta. This activity was detected by radioimmunoassay from day 50 (D50) until the end of pregnancy. Higher IR-GHRH concentration in placental tissue was observed on days 100 (543 +/- 123 pg/g) and 140 (550 +/- 62 pg/g) and, when compared with the GHRH content of the ovine hypothalamus (1.2 ng/hypothalamus), represents a considerable amount of GHRH per placenta (a mean of 200 ng). Perifused placenta explants released IR-GHRH in vitro at a mean rate of 200 pg/g/h. Depolarization by 55 mM KCl increased the IR-GHRH concentration of the perifusion media 1.7 times over basal values. The elution position of GHRH immunoreactivity in the gel filtration chromatography profiles was the same for placenta and hypothalamus extracts and lay very near to the molecular weight of bovine GHRH. Northern blot hybridization analysis revealed the existence of a placental transcript whose size (0.75 kb) was comparable to the size of the ovine hypothalamus and rat placenta GHRH transcripts. Hybridization signal was observed at each stage studied from D50 until D120 of pregnancy. This study demonstrated the existence of a IR-GHRH peptide in the ovine placenta.
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38

Yang, Ling, Luyu Wang, Jiaxuan Wu, Haichao Wang, Gengxin Yang y Leying Zhang. "Changes in Expression of Complement Components in the Ovine Spleen during Early Pregnancy". Animals 11, n.º 11 (8 de noviembre de 2021): 3183. http://dx.doi.org/10.3390/ani11113183.

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During early gestation in humans, complement regulation is essential for normal fetal growth. It is supposed that a complement pathway participates in maternal splenic immune regulation at the early stage of gestation in ewes. The aim of this study was to analyze the effects of early pregnancy on the expression of complement components in the maternal spleen of ewes. In this study, ovine spleens were sampled on day 16 of nonpregnancy, and days 13, 16 and 25 of gestation. RT-qPCR, Western blot and immunohistochemical analysis were used to detect the changes in expression of complement components in the ovine maternal spleens. Our results reveal that C1q was upregulated during early gestation, C1r, C1s, C2, C3 and C5b increased at day 25 of gestation and C4a and C9 peaked at days 13 and 16 of gestation. In addition, C3 protein was located in the capsule, trabeculae and splenic cords. In conclusion, our results show for the first time that there was modification in the expression of complement components in the ovine spleen at the early stage of gestation, and complement pathways may participate in modulating splenic immune responses at the early stage of gestation.
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39

Zhang, Leying, Chen Zhuang, Zimo Zhao, Ning Li, Jiachen Bai y Ling Yang. "Effect of early pregnancy on the expression of progesterone receptor and progesterone-induced blocking factor 1 in ovine liver". Czech Journal of Animal Science 64, No. 7 (17 de julio de 2019): 317–23. http://dx.doi.org/10.17221/21/2019-cjas.

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Liver plays important roles in the innate and adaptive immunity, and contributes to the maternal immune adjustments during pregnancy. Progesterone (P4) has key effects on immunomodulation of the maternal uterus during pregnancy. In this study, livers were obtained at day 16 of the estrous cycle and at days 13, 16 and 25 of pregnancy (n = 6 for each group) in ewes. The effects of early pregnancy on the expression of P4 receptor (PGR) and progesterone-induced blocking factor 1 (PIBF1) were analysed through RT-qPCR assay, Western blot and immunohistochemistry analysis. Our results showed that the isoforms of PGR with molecular weights of approximately 60 kDa (PGR60) and 89 kDa (PGR89) were strongly expressed in the livers from pregnant ewes (P &lt; 0.05), but there was no expression of the isoform of PIBF1 with a molecular weight of approximately 55 kDa (PIBF55) on day 13 of pregnancy. The PGR protein was mainly limited to the endothelial cells of the proper hepatic arteries and portal veins, and hepatic cells. In conclusion, the PGR89 and PGR60 were up-regulated, and PIBF55 was down-regulated on day 13 of pregnancy, which may be involved in maternal hepatic immunoregulation during early pregnancy in sheep.
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40

Rovani, Monique Tomazele, Alfredo Skrebsky Cezar, Melânia Lazzari Rigo, Bernardo Garziera Gasperin, Janduí Escarião da Nóbrega Júnior, Fabrício Dias Torres, Paulo Bayard Dias Gonçalves y Rogério Ferreira. "Evaluation of a bovine pregnancy-associated glycoprotein enzyme-linked immunosorbent assay kit for serological diagnosis of pregnancy in sheep". Ciência Rural 46, n.º 2 (27 de noviembre de 2015): 362–67. http://dx.doi.org/10.1590/0103-8478cr20150270.

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ABSTRACT: Pregnancy diagnosis is an important tool for farm management. Ultrasonography is the main technique used for pregnancy diagnosis in ewes. As an alternative, radioimmunoassay (RIA) allows accurate and early detection of pregnancy-associated glycoproteins (PAGs) in sheep blood. However, radioactive-based techniques, as RIA, have been increasingly inadvisable due to environmental risk. Homology between ovine and bovine PAGs is high, and ELISA kits used for PAGs detection in cattle are safer than RIA. Thus, this study aimed to evaluate the feasibility of PAGs detection for pregnancy diagnosis in sheep serum samples using an ELISA kit produced for cattle. The sensitivity and specificity of the ELISA kit were 93.5% and 98.9%, respectively, whereas positive and negative predictive values were 99.0% and 93.1%, respectively, in comparison to ultrasonography diagnostic (control). PAGs reached consistently detectable concentrations in ovine serum around 33 days after mating. Accuracy of the ELISA test was 96.1% from 33 days of pregnancy until lambing. After parturition, PAGs were still detectable seven days post-lambing. However, from 21 days post-parturition, PAGs from the previous pregnancy were no longer detected in serum samples. In conclusion, the bovine ELISA kit can accurately detect pregnancy in sheep 33 days following mating, while PAGs levels from the previous gestation are no longer detected from 21 days post-partum. The evaluated ELISA test is a reliable tool for pregnancy diagnosis in sheep at random stages and as a complementary exam at early gestation.
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41

Palmarini, Massimo, C. Allison Gray, Karen Carpenter, Hung Fan, Fuller W. Bazer y Thomas E. Spencer. "Expression of Endogenous Betaretroviruses in the Ovine Uterus: Effects of Neonatal Age, Estrous Cycle, Pregnancy, and Progesterone". Journal of Virology 75, n.º 23 (1 de diciembre de 2001): 11319–27. http://dx.doi.org/10.1128/jvi.75.23.11319-11327.2001.

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ABSTRACT The ovine genome contains 15 to 20 copies of endogenous retroviruses (enJSRVs) highly related to the oncogenic jaagsiekte sheep retrovirus (JSRV) and enzootic nasal tumor virus. enJSRVs are highly expressed in the endometrial lumenal epithelia (LE) and glandular epithelia (GE) of the ovine uterus. The effects of neonatal age, estrous cycle, pregnancy, and progesterone on expression of enJSRVs in the ovine uterus were determined. Expression of enJSRV RNAs was absent from the uterus of ewes at birth, but enJSRV RNAs were expressed specifically in the LE and developing GE from postnatal day (PND) 7 to PND 56. In adult ewes, enJSRV RNAs were detected only in the epithelia of the uterine endometrium, as well as epithelia of the oviduct, cervix, and vagina. In cyclic ewes, endometrial enJSRV RNA abundance was lowest on day 1, increased 12-fold between days 1 and 13, and then decreased to day 15. In pregnant ewes, levels of endometrial enJSRV RNAs were high on day 11, increased to day 13, and then decreased to day 19. In day 17 and 19 conceptuses, enJSRV RNAs were also detected in binucleate cells of the trophectoderm. Immunoreactive JSRV capsid and envelope proteins were detected in the endometrial LE and GE, as well as in the binucleate cells of the conceptus. In transfection assays utilizing ovine endometrial LE cells, progesterone increased transcriptional activity of several enJSRV long terminal repeats. Collectively, these results indicate that transcription of enJSRVs in the endometrial epithelia of the ovine uterus is increased by progesterone and might support a role for enJSRVs in conceptus-endometrium interactions during the peri-implantation period and early placental morphogenesis.
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42

MUSA, S. I., K. O. YAHAYA y A. YAHAYA. "COMPUTATIONAL ANALYSIS OF FUNCTIONAL EFFECTS OF SINGLE NUCLEOTIDE POLYMORPHISM ON OVINE INTERFERON TAU". FUDMA Journal of Agriculture and Agricultural Technology 8, n.º 1 (15 de septiembre de 2022): 26–29. http://dx.doi.org/10.33003/jaat.2022.0801.071.

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The objective of this study was to evaluate the functional effects of Single Nucleotide Polymorphism(SNP) in ovine interferon tau using computational methods. Data on ovine interferon was retrieved from data base of National Center for Biotechnology Information ((GenBank). Functional effects of substitution of Leucin by Proline at position 26 of interferon protein chain was predicted using Protein Variation Effect Analyser, Panther server and Poly phen 2 (Polymorphism phenotyping). Provean score of - 5.828 was obtained, indicating a deleterious effect of the amino acid substitution. Panther server indicated damaging effect of the SNP with Pdel ( probability of deleterious effect) of 0.5. Similarly, Poly phen 2 showed damaging effect of the amino acid substitution. It can be concluded that substitution of Leucin by proline at position 26 of the protein sequence of interferon tau resulted in deleterious effect on the functionality of ovine interferon tau. Studies in Single Nucleotide Polymorphism on ovine interferon tau can provide better understanding of biomarkers associated with efficiency of maternal pregnancy recognition in the ovine species.
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43

Song, Gwonhwa, Jo-Ann G. W. Fleming, Jinyoung Kim, Thomas E. Spencer y Fuller W. Bazer. "Pregnancy and interferon τ regulate DDX58 and PLSCR1 in the ovine uterus during the peri-implantation period". REPRODUCTION 141, n.º 1 (enero de 2011): 127–38. http://dx.doi.org/10.1530/rep-10-0348.

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Interferon τ (IFNT), the pregnancy recognition signal in ruminants, abrogates the luteolytic mechanism for maintenance of the corpus luteum for production of progesterone (P4). This study examined the expression of DEAD (Asp-Glu-Ala-Asp) box polypeptide 58 (DDX58) and phospholipid scramblase 1 (PLSCR1) mRNAs in the ovine uterus as these genes were increased most in 2fTGH (STAT1 positive) cells by IFNT. The results of this study indicated that IFNT regulates expression ofDDX58andPLSCR1mRNAs in the ovine uterus, which confirmed the results of thein vitrotranscriptional profiling experiment with the 2fTGH (parental STAT1 positive) and U3A (STAT1 null) cell lines. Steady-state levels ofDDX58andPLSCR1mRNAs increased in cells of the ovine uterus between days 12 and 20 of pregnancy, but not between days 10 and 16 of the estrous cycle. The expression ofDDX58andPLSCR1mRNAs was greatest in endometrial stromal cells, but there was transient expression in uterine luminal and superficial glandular epithelial cells. P4alone did not induce expression ofDDX58andPLSCR1mRNAs; however, intrauterine injections of IFNT did induce expression ofDDX58andPLSCR1mRNAs in the endometria of nonpregnant ewes independent of effects of P4. These results indicate that IFNT induces expression ofDDX58andPLSCR1in ovine endometrial cells via the classical STAT1-mediated cell signaling pathway. Based on their known biological effects,DDX58andPLSCR1are IFN-stimulated genes, which may increase the antiviral status of cells of the pregnant uterus to protect against viral infection and/or enhance secretion of type I IFNs that inhibit viral replication.
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44

Salamonsen, LA y JK Findlay. "Regulation of endometrial prostaglandins during the menstrual cycle and in early pregnancy". Reproduction, Fertility and Development 2, n.º 5 (1990): 443. http://dx.doi.org/10.1071/rd9900443.

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Prostaglandins are important regulators of endometrial function. In turn, their secretion is controlled by endocrine and paracrine mediators. Cyclical effects of ovarian oestrogen and progesterone throughout the menstrual or oestrous cycle result in overall higher levels of prostaglandin release during the secretory or luteal phase of the cycle than during the proliferative phase. Potential paracrine regulators of endometrial origin include cytokines, growth factors and histamine, some of which may arise from infiltrating cells. Embryo-derived factors can regulate endometrial prostaglandin release in early pregnancy. Both platelet-activating factor and ovine trophoblast protein-1 (an embryonic interferon) modify prostaglandin release from primary cultures of endometrial cells of human and ovine origin respectively. Manipulation of such mediators may provide new means for fertility control.
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45

Quillen, E. W. y B. S. Nuwayhid. "Steady-state arterial pressure-urinary output relationships during ovine pregnancy". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 263, n.º 5 (1 de noviembre de 1992): R1141—R1146. http://dx.doi.org/10.1152/ajpregu.1992.263.5.r1141.

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To determine the effects of long-term changes in sodium intake on mean arterial pressure (MAP) regulation during pregnancy, nonpregnant (n = 16) and 110- to 140-day pregnant (n = 13) ewes received total daily sodium intakes of 10, 30, 100, 400, and 1,200 mmol for 7 days. The sheep were housed in metabolism cages and MAP was monitored 24 h/day. Urinary sodium excretion (UNaV) followed changes in sodium intake, with steady-state levels being achieved with similar degrees of rapidity (2-3 days) in nonpregnant and pregnant sheep. At 10 mmol/day sodium intake, MAP was lower (79 +/- 1 vs. 82 +/- 2 mmHg; P < 0.01) and water intake (2,275 +/- 494 vs. 3,286 +/- 725 ml/day; P < 0.001) and 24-h urine volume (1,454 +/- 279 vs. 2,299 +/- 496 ml/day; P < 0.01) were greater in pregnant sheep. All of these variables exhibited direct relationships with increases in sodium intake. Plasma angiotensin II (pANG II) was increased in pregnancy (10.6 +/- 1.6 vs. 24.5 +/- 6.3 pg/ml; P < 0.001) at 10 mmol/day. Elevation of sodium intake suppressed pANG II to minimal levels in nonpregnant sheep, but to only 25% of the control level in pregnant sheep. During pregnancy, the renal function curve representing the steady-state MAP-UNaV relationship was shifted to lower MAP setpoint, but the sodium sensitivity of MAP was unchanged. Also, the inverse relationship of sodium intake and pANG II was blunted, suggesting a reduced role for ANG II in the maintenance of renal function during pregnancy.
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46

Wang, Yujiao, Xu Han, Leying Zhang, Nan Cao, Lidong Cao y Ling Yang. "Early Pregnancy Induces Expression of STAT1, OAS1 and CXCL10 in Ovine Spleen". Animals 9, n.º 11 (30 de octubre de 2019): 882. http://dx.doi.org/10.3390/ani9110882.

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Interferon-tau is a maternal recognition factor in ruminant species, and spleen plays an essential role in regulating innate and adaptive immune responses. However, it is not fully understood that early pregnancy induces expression of interferon stimulated genes (ISGs) in the spleen during early pregnancy in ewes. In this study, spleens were collected from ewes at day 16 of the estrous cycle, and on days 13, 16, and 25 of gestation (n = 6 for each group), and RT-qPCR, western blot and immunohistochemistry analysis were used to detect the expression of signal transducer and activator of transcription 1 (STAT1), 2′,5′-oligoadenylate synthetase 1 (OAS1), myxovirusresistance protein 1 (Mx1) and C-X-C motif chemokine 10 (CXCL10). The results revealed that STAT1, OAS1 and CXCL10 mRNA and proteins were upregulated in the spleens during early pregnancy, and STAT1 protein was located in connective tissue cells in the capsule and trabeculae, and blood cells and lymphocytes in the red pulp. However, early pregnancy had no significant effects on expression of MX1 mRNA and protein. In conclusion, early pregnancy induces expression of STAT1, OAS1 and CXCL10 in maternal spleen, suggesting that maternal spleen is involved in immune regulation of pregnancy in sheep.
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47

Romero, Jared J., Alfredo Q. Antoniazzi, Natalia P. Smirnova, Brett T. Webb, Fang Yu, John S. Davis y Thomas R. Hansen. "Pregnancy-associated genes contribute to antiluteolytic mechanisms in ovine corpus luteum". Physiological Genomics 45, n.º 22 (15 de noviembre de 2013): 1095–108. http://dx.doi.org/10.1152/physiolgenomics.00082.2013.

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The hypothesis that ovine luteal gene expression differs due to pregnancy status and day of estrous cycle was tested. RNA was isolated from corpora lutea (CL) on days 12 and 14 of the estrous cycle (NP) or pregnancy (P) and analyzed with the Affymetrix bovine microarray. RNA also was isolated from luteal cells on day 10 of estrous cycle that were cultured for 24 h with luteolytic hormones (OXT and PGF) and secretory products of the conceptus (IFNT and PGE2). Differential gene expression (>1.5-fold, P < 0.05) was confirmed using semiquantitative real-time PCR. Serum progesterone concentrations decreased from day 12 to day 15 in NP ewes ( P < 0.05) reflecting luteolysis and remained >1.7 ng/ml in P ewes reflecting rescue of the CL. Early luteolysis ( days 12–14) was associated with differential expression of 683 genes in the CL, including upregulation of SERPINE1 and THBS1. Pregnancy on day 12 (55 genes) and 14 (734 genes) also was associated with differential expression of genes in the CL, many of which were ISGs (i.e., ISG15, MX1) that were induced when culturing luteal cells with IFNT, but not PGE2. Finally, many genes, such as PTX3, IL6, VEGF, and LHR, were stabilized during pregnancy and downregulated during the estrous cycle and in response to culture of luteal cells with luteolytic hormones. In conclusion, pregnancy circumvents luteolytic pathways and activates or stabilizes genes associated with interferon, chemokine, cell adhesion, cytoskeletal, and angiogenic pathways in the CL.
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48

Galio, Laurent, Stéphanie Droineau, Patrick Yeboah, Hania Boudiaf, Stephan Bouet, Sandrine Truchet y Eve Devinoy. "MicroRNA in the ovine mammary gland during early pregnancy: spatial and temporal expression of miR-21, miR-205, and miR-200". Physiological Genomics 45, n.º 4 (15 de febrero de 2013): 151–61. http://dx.doi.org/10.1152/physiolgenomics.00091.2012.

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The mammary gland undergoes extensive remodeling between the beginning of pregnancy and lactation; this involves cellular processes including cell proliferation, differentiation, and apoptosis, all of which are under the control of numerous regulators. To unravel the role played by miRNA, we describe here 47 new ovine miRNA cloned from mammary gland in early pregnancy displaying strong similarities with those already identified in the cow, human, or mouse. A microarray study of miRNA variations in the adult ovine mammary gland during pregnancy and lactation showed that 100 miRNA are regulated according to three principal patterns of expression: a decrease in early pregnancy, a peak at midpregnancy, or an increase throughout late pregnancy and lactation. One miRNA displaying each pattern (miR-21, miR-205, and miR-200b) was analyzed by qRT-PCR. Variations in expression were confirmed for all three miRNA. Using in situ hybridization, we detected both miR-21 and miR-200 in luminal mammary epithelial cells when expressed, whereas miR-205 was expressed in basal cells during the first half of pregnancy and then in luminal cells during the second half. We therefore conclude that miR-21 is strongly expressed in the luminal cells of the normal mammary gland during early pregnancy when extensive cell proliferation occurs. In addition, we show that miR-205 and miR-200 are coexpressed in luminal cells, but only during the second half of pregnancy. These two miRNA may cooperate to maintain epithelial status by repressing an EMT-like program, to achieve and preserve the secretory phenotype of mammary epithelial cells.
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49

Gray, C. Allison, Kathrin A. Dunlap, Robert C. Burghardt y Thomas E. Spencer. "Galectin-15 in ovine uteroplacental tissues". Reproduction 130, n.º 2 (agosto de 2005): 231–40. http://dx.doi.org/10.1530/rep.1.00637.

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Galectin-15 is the newest member of a secreted β-galactoside-binding lectin family. The galectin-15 gene is expressed specifically by the endometrial luminal epithelium (LE) and superficial ductal glandular epithelium (sGE) of the ovine uterus. The proposed extracellular role of secreted galec7tin-15 is to regulate implantation and placentation by functioning as a heterophilic cell adhesion molecule between the conceptus trophectoderm and endometrial LE, while that of intracellular galectin-15 is to regulate cell survival, differentiation and function. The present study determined galectin-15 expression in uteroplacental tissues during gestation and in the postpartum uterus. In the uterine lumen, secreted galectin-15 was found as multimers, particularly on days 14 and 16 of pregnancy. In the endometrial epithelium and conceptus trophectoderm, intracellular galectin-15 protein was found associated with crystalline structures. Between days 20 and 120 of pregnancy, galectin-15 mRNA was expressed specifically by the LE and sGE of the intercaruncular endometrium of ewes. Immunoreactive galectin-15 protein was most abundant in the trophectoderm with lower levels in the endometrial LE and sGE. Galectin-15 protein was detected in allantoic fluid, but not in amniotic fluid. After parturition, galectin-15 mRNA declined in the endometrium from postpartum day (PPD) 1 to 28 and exhibited a variegated expression pattern in the LE and sGE. These results indicate that galectin-15 is synthesized and secreted throughout gestation by the endometrial LE/sGE and is absorbed by the placenta and forms crystals within the trophectoderm, whereas the remainder is cleared into the allantois after being transported into the fetal circulation via the placental areolae. Based on the biological properties of other galectin family members, galectin-15 is hypothesized to have biological roles in conceptus–endometrial interactions, uterine immune and inflammatory responses, and placental morphogenesis and function.
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50

Wong, M. H. y G. E. Rice. "Characterisation of acyltransferase activity in ovine placental tissue during pregnancy and at the time of labour". Journal of Endocrinology 148, n.º 2 (febrero de 1996): 241–47. http://dx.doi.org/10.1677/joe.0.1480241.

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Abstract Although it is well established that the formation of eicosanoids by ovine intrauterine tissues increases during pregnancy and at the time of labour, the biochemical mechanisms involved remain to be clearly established. In this study, we tested the hypothesis that the gestational and labour-associated increases in eicosanoid formation are associated with a reduction in the activity of the reacylating enzyme, acyl Coenzyme A lysophosphatide acyltransferase (LAT). To evaluate this proposal, in vitro LAT activity was quantified in ovine placenta (cotyledons) obtained during pregnancy (85–147 days of gestation and at the time of labour). Ovine placental LAT increased from 1·81 ± 0·06 nmol/min per mg protein at 85 days of gestation to 2·34 ± 0·10 nmol/min per mg protein at 142 days of gestation (P<0·005, n=15). The apparent Km did not vary significantly between the 85- and 142-day groups. Vmax, however, was significantly greater in the late-gestation group (2·98 ± 0·02 nmol/min per mg protein) than in the mid-gestation group (2·38 ± 0·13 nmol/min per mg protein, P<0·05). In association with labour, placental LAT activity decreased by 16% (1·96 ± 0·13 nmol/min per mg protein) when compared with that observed in tissue obtained from the non-labouring ewe (P<0·01). The data obtained are consistent with the hypothesis that changes in LAT activity in ovine placenta do not contribute to the gestational increase in prostaglandin formation, but a contribution to the labour-associated increase in non-esterified arachidonic acid availability and eicosanoid formation cannot be negated. Journal of Endocrinology (1996) 148, 241–247
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