Roles of prostaglandins (PG) F2 alpha, E1, E2, adenosine, oestradiol-17 beta, histone-H2A and progesterone of conceptus, uterine or ovarian origin during early and mid pregnancy in the ewe

1992 ◽  
Vol 4 (3) ◽  
pp. 289 ◽  
Author(s):  
CW Weems ◽  
DL Vincent ◽  
YS Weems
Keyword(s):  
Corpus Luteum ◽  
Early Pregnancy ◽  
Histone H2a ◽  
Prostaglandin F2 Alpha ◽  
Venous Plasma ◽  
Local Transfer

Pregnancy does not prevent the local transfer or accumulation of prostaglandin F2 alpha (PGF2 alpha) by the corpus luteum (CL), the number of receptors for PGF2 alpha or the binding of PGF2 alpha to the CL. However, the conceptus does depress the response of the CL to PGF2 alpha during early pregnancy. PGE1 and PGE2 appear to be blood-borne antiluteolysins that are delivered locally to prevent the actions of PGF2 alpha during early pregnancy, since they prevent luteolysis only when given by chronic intrauterine infusion adjacent to the ovary with the CL. The concentrations of PGE1 and PGE2 in the endometrium and PGE2 in uterine venous plasma increase during early pregnancy. A Day 10 embryo transferred to a Day 6 progestagen-primed recipient ewe advances the time at which PGE2 is secreted. The uterine venous PGE/PGF2 alpha ratio is 12:1 at midgestation, and exogenous PGF2 alpha increases the placental secretion of oestradiol-17 beta. This is followed by increases in PGE secretion when endogenous PGF2 alpha increases. Both oestradiol-17 beta and PGE may protect placental secretion of progesterone from PGF2 alpha, since PGF2 alpha causes the CL to regress but does not affect placental progesterone or pregnancy in the presence or absence of the ovary.

Oxytocin-induced prostaglandin F2-alpha release is low in early bovine pregnancy but increases during the second month of pregnancy†

2019 ◽  
Author(s):  
Jéssica N Drum ◽  
Milo C Wiltbank ◽  
Pedro L J Monteiro ◽  
Alexandre B Prata ◽  
Rodrigo S Gennari ◽  
...  
Keyword(s):  
Corpus Luteum ◽  
Early Pregnancy ◽  
Artificial Insemination ◽  
Peripheral Blood ◽  
Prostaglandin F2α ◽  
Peripheral Blood Leukocytes ◽  
Blood Leukocytes ◽  
Interferon Stimulated Genes ◽  
Prostaglandin F2 Alpha ◽  
Oxytocin Receptors

Abstract Circulating prostaglandin F2α metabolite (PGFM) after an oxytocin challenge was evaluated throughout the first 2 months of pregnancy in lactating Holstein cows. On day 11, 18, and 25 after artificial insemination (AI), and on days 32, 39, 46, 53, and 60 of pregnancy, cows were challenged with 50 IU oxytocin, i.m. Blood was collected before (0 min), 30, 60, 90, and 120 min after oxytocin for plasma PGFM concentrations. Ultrasound evaluations were performed for pregnancy diagnosis on day 32–60 post-AI. Nonpregnant (NP) cows on day 18 were designated by a lack of interferon-stimulated genes in peripheral blood leukocytes and Pregnant (P) based on day 32 ultrasound. On day 11, P and NP were similar with low PGFM and no effect of oxytocin on PGFM. On day 18, oxytocin increased PGFM (3-fold) in NP with little change in P cows. Comparing only P cows from day 11 to 60, basal circulating PGFM increased as pregnancy progressed, with day 11 and 18, lower than all days from day 25 to 60 of pregnancy. Oxytocin-induced PGFM in P cows on day 25 was greater than P cows on day 18 (2.9-fold). However, oxytocin-induced PGFM was lower on day 25 compared to day 53 and 60, with intermediate values on day 32, 39, and 46 of pregnancy. Thus, the corpus luteum (CL) of early pregnancy (day 11, 18) is maintained by suppression of PGF, as reflected by suppressed PGFM in this study. However, during the second month of pregnancy, uterine PGF secretion was not suppressed since basal PGFM and oxytocin-induced PGFM secretion were elevated. Apparently, mechanisms other than suppression of oxytocin receptors maintain CL after day 25 of pregnancy.

Interaction between oxytocin and prostaglandin F2 alpha during luteal regression and early pregnancy in sheep

1992 ◽  
Vol 4 (3) ◽  
pp. 321 ◽  
Author(s):  
G Jenkin
Keyword(s):  
Corpus Luteum ◽  
Early Pregnancy ◽  
Peripheral Circulation ◽  
Oxytocin Receptor ◽  
Secretory Proteins ◽  
Luteal Regression ◽  
Pulsatile Release ◽  
Major Mechanism ◽  
Prostaglandin F2 Alpha ◽  
Oxytocin Receptors

The pulsatile release of oxytocin from the corpus luteum in the sheep is responsible for the pulsatile release of prostaglandin F2 alpha (PGF2 alpha) from the uterus at luteolysis. It has been proposed that PGF2 alpha also reinforces this process by stimulating the release of oxytocin from the corpus luteum. It is, however, unlikely that PGF2 alpha is the major stimulus for oxytocin release at this time. Although the stimulus for the pulsatile release of oxytocin from the corpus luteum appears to reach the ovary from the peripheral circulation, the nature of the stimulus is unknown. Pulses of oxytocin originating from the corpus luteum have also been observed during early pregnancy, but the release of PGF2 alpha, in response to this signal, is abrogated in some way by ovine trophoblast protein-1 (oTP-1). This protein has been shown to inhibit endometrial prostaglandin production and to decrease the amount of PGF2 alpha released in response to oxytocin. Reduction of uterine oxytocin receptor concentrations by conceptus secretory proteins or by interferons related to oTP-1 remains equivocal. Inhibition of uterine oxytocin receptors is, however, probably the major mechanism that prevents luteal regression during early pregnancy. In cyclic sheep the specific inhibition of uterine oxytocin receptors by 1-deamino-2-D-Try (oET)-4-Thr-8-Orn-oxytocin (CAP), a synthetic oxytocin receptor antagonist, inhibits luteal regression and suppresses pulsatile, but not basal, secretion of uterine PGF2 alpha. Thus, the effects of CAP directly parallel the endocrinological changes that occur in early pregnancy in the sheep.

Corpus luteum blood flow in abnormal early pregnancy.

1996 ◽  
Vol 15 (9) ◽  
pp. 645-649 ◽  
Author(s):  
J L Alcázar ◽  
C Laparte ◽  
G López-Garcia
Keyword(s):  
Blood Flow ◽  
Corpus Luteum ◽  
Early Pregnancy

Sources of progesterone during gestation in Barbary sheep (Ammotragus lervia)

1983 ◽  
Vol 98 (2) ◽  
pp. 283-NP ◽  
Author(s):  
A. P. F. Flint ◽  
R. D. Burton ◽  
R. B. Heap
Keyword(s):  
Chromosome Number ◽  
Corpus Luteum ◽  
Late Pregnancy ◽  
Hydroxysteroid Dehydrogenase ◽  
Point Of View ◽  
Diploid Chromosome Number ◽  
Domestic Sheep ◽  
Ammotragus Lervia ◽  
Barbary Sheep ◽  
Venous Plasma

Concentrations of progesterone in arterial and ovarian, uterine and jugular venous plasma were determined in four Barbary sheep at various stages of pregnancy. The results, together with ovarian histology, show that the corpus luteum regresses before term in Barbary sheep, as in most breeds of domestic ewes. Uterine synthesis of progesterone was demonstrated in late pregnancy in two animals in which uterine venous levels of progesterone were increased two- to fourfold above arterial concentrations. The placenta contained 3β-hydroxysteroid dehydrogenase. Barbary sheep (diploid chromosome number, 2N = 58) therefore resemble the domestic sheep (2N = 54) rather than the goat (2N = 60) from the point of view of the source of the progesterone required for maintenance of pregnancy.

17. Aberrant corpus luteum number as a contributor to altered maternal vascular health in early pregnancy and preeclampsia risk after assisted reproduction

2018 ◽  
Vol 13 ◽  
pp. S16
Author(s):  
Frauke von Versen-Höynck ◽  
Purnima Narasimhan ◽  
Elif Seda Selamet Tierney ◽  
Nadine Martinez ◽  
Kirk P. Conrad ◽  
...  
Keyword(s):  
Corpus Luteum ◽  
Assisted Reproduction ◽  
Early Pregnancy ◽  
Vascular Health

Blood perfusion and diameter of bovine corpus luteum as predictors of luteal function in early pregnancy

2021 ◽  
Author(s):  
Gabriella dos Santos Velho ◽  
Monique Tomazele Rovani ◽  
Rogério Ferreira ◽  
Bernardo Garziera Gasperin ◽  
André Gustavo Cabrera Dalto
Keyword(s):  
Corpus Luteum ◽  
Early Pregnancy ◽  
Blood Perfusion ◽  
Luteal Function ◽  
Bovine Corpus Luteum
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