Effect of Oestrogen Antagonist (Tamoxifen) on Steroid Hormone Levels, Maturation Process of Placentomes and Course of Late Pregnancy in Cows

Janowski, Tomasz; Zduńczyk, S; Podhalicz-Dzitjgielewska, M.; Race, Amanda D.; Chmielewski, Annette

doi:10.1111/j.1439-0531.1996.tb00089.x

Cited by 8 publications

(5 citation statements)

References 21 publications

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“…Equally the role of placental estrogens in cattle is far from being clear mainly due to the lack of a method for the selective disruption of placental estrogen production. When the estrogen receptor blocker tamoxifen was applied to late pregnant cows from day 265 of gestation until parturition, no signifi cant effect could be demonstrated on the calving process, incidence of placental retention, maternal estrogen levels and placentomal histology ( Janowski et al, 1996 ). These results argue against an essential role of placental estrogens in the regulation of placental morphology and functions.…”

Section: Discussionmentioning

confidence: 97%

Placental Steroids in Cattle: Hormones, Placental Growth Factors or By-products of Trophoblast Giant Cell Differentiation?

Schuler¹,

Greven²,

Kowalewski³

et al. 2008

Exp Clin Endocrinol Diabetes

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The bovine placenta produces large amounts of steroids, mainly estrone (E1) and progesterone (P4). Specific features of bovine placental steroidogenesis are 1) the expression of all enzymes needed for the production of estrogens from cholesterol in the trophoblast 2) an only marginal and temporal contribution to peripheral maternal P4 levels restricted to a period between approx. days 150 - 240 of gestation 3) the predominance of sulfoconjugated over free E1 and 4) a complementary setting of steroidogenic enzymes in the two morphologically discriminable trophoblast cell types, the uninucleated trophoblast cells (UTC) and the trophoblast giant cells (TGC). In cattle so far no definite information is available on the specific biological roles of placental estrogens and P4. However, the detection of estrogen receptors and progesterone receptors in the placentomes suggests a role primarily as local regulators of caruncular growth, differentiation and functions. Inconsistent with a function as a caruncular growth factor is the strong evidence that in cattle placental estrogens enter the maternal compartment almost completely as estrone sulfate (E1S), which is not active at classical nuclear receptors. On the other hand, E1S may be converted locally to free active estrogens via the action of steroid sulfatase (StS), which has been detected in specific parts of the bovine caruncular epithelium. Alternatively or in addition, StS expression in the caruncular epithelium may serve the utilization of sulfated neutral steroid precursors (e.g. pregnenolone sulfate or cholesterol sulfate) supplied with maternal blood, thus providing free substrates for further metabolization in the adjacent trophoblast. The down-regulation of P450scc and P450c17 and the up-regulation of 3beta-HSD and aromatase during the differentiation of TGC from UTC in parallel with the up-regulation of ER beta and estrogen sulfotransferase in maturing TGC suggests a function of placental estrogens primarily as autoor intracrine regulators during this process and assigns to conjugated placental estrogens a role as inactivated by-products of TGC differentiation intended for excretion. Collectively, despite some evidence from recent studies for putative roles of placental steroids in cattle their exact functions in the bovine species remain still undefined.

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Section: Discussionmentioning

confidence: 97%

Placental Steroids in Cattle: Hormones, Placental Growth Factors or By-products of Trophoblast Giant Cell Differentiation?

Schuler¹,

Greven²,

Kowalewski³

et al. 2008

Exp Clin Endocrinol Diabetes

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“…As discussed above for humans, other roles of placental estrogens may have remained undetected as suppression of placental estrogen production was incomplete. Janowski et al (1996) applied the estrogen receptor antagonist tamoxifen to pregnant cows starting on day 240 until parturition to block the effects of placental estrogens. Animals of the treatment group had significantly lower progesterone concentrations between days -9 to -2 before parturition, but no effects were observed on gestational length, calving, neonatal viability, incidence of placental retention and placental histomorphology.…”

Section: Placental Estrogensmentioning

confidence: 99%

Section: The Placenta As An Endocrine Organ During Pregnancymentioning

confidence: 99%

Placental contribution to the endocrinology of gestation and parturition

Schuler¹,

Fürbaß²,

Klisch

2018

Anim Reprod

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In addition to many other functions, the placenta is a source of a vast number of autocrine, paracrine and endocrine factors. However, the spectrum of placental regulatory factors, their concentrations, gestational profiles and roles may differ considerably even between phylogenetically closely related species. Depending on the species, placental regulatory factors of a broad range of molecule classes have been found including (glyco-)proteins, peptides, steroids and prostaglandins. Local placental regulatory factors are especially important for the dialogue between the fetal and the maternal compartment immediately at the feto-maternal borderline and for the control of growth, differentiation and functions of the placenta itself. Moreover, placental hormones in a proper sense may also have effects in more remote targets within the maternal compartment, serving functions such as pregnancy-specific adaptations of maternal circulation, provision of hemotrophe to the fetus or the development and function of the mammary gland. Functions of placental hormones in the fetus proper are less clear but may be especially important before the establishment of a functional fetal endocrine system and near term within the highly species-specific networks of signals preparing and initiating parturition. This review takes a comparative view on the situation in different domestic animals focusing on ruminants and on placental hormones occurring at significant concentrations in the maternal circulation.

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“…Prostaglandins F2α and E2 play significant roles in the regulation of blood flow, especially in the fetal part of the placenta (Maigaard et al 1986, Poston 1997, and are also regulators of uterine contractile activity (Ruckebusch and Bayard 1975). Furthermore, PGE2 together with progesterone regulates the growth and development of the placentomes (Robertson et al 1979, Janowski et al 1996. In bovine placenta, PGs are synthesized and released within cotyledons and endometrium in interplacentomal areas.…”

Section: Introductionmentioning

confidence: 99%

Polish Journal of Veterinary Sciences

Mlynarczuk

Wróbel

Dobrzyn

2020

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Dieldrin and DDE are environmental metabolites of the organochlorine pesticides aldrin and DDT, respectively. During pregnancy, these chemicals can quickly infiltrate through the placental barrier, accumulate in amniotic fluid and fetus, and act as endocrine disruptors (EDs). The aim of this study was to investigate the effect of DDE and dieldrin and their parental substances at concentrations of 1 and 10 ng/ml on secretion of PGE2 and PGF2α from bovine endometrial explants (120-150 and 151-180 days of pregnancy) after 24 hr of incubation with EDs. The mRNA expression of COX2, PGES and PGFS and the concentrations of PGE2 and PGF2α were measured. EDs did not affect (p>0.05) COX2 gene expression, but DDT and DDE decreased (p<0.05) PGES expression and PGE2 secretion in the explants from 120-150 days of pregnancy. Depending on the dose, DDT and DDE increased (p<0.05) PGFS expression and PGF2α secretion from the explants from 120-150 days and decreased PGF2α secretion (p<0.05) from the explants from 151-180 days of pregnancy. Aldrin and dieldrin decreased (p<0.05) PGFS expression and PGF2α secretion from all explants. In summary, EDs disrupt the secretion of PGE2 and PGF2α by influencing the gene expression of PGES and PGFS.

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Effect of Oestrogen Antagonist (Tamoxifen) on Steroid Hormone Levels, Maturation Process of Placentomes and Course of Late Pregnancy in Cows

Cited by 8 publications

References 21 publications

Placental Steroids in Cattle: Hormones, Placental Growth Factors or By-products of Trophoblast Giant Cell Differentiation?

Placental Steroids in Cattle: Hormones, Placental Growth Factors or By-products of Trophoblast Giant Cell Differentiation?

Placental contribution to the endocrinology of gestation and parturition

Polish Journal of Veterinary Sciences

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