Changes in plasma levels of estrone sulfate and estrone in the pregnant ewe around parturition

Tsang, Charles P.W.

doi:10.1016/0039-128x(74)90059-2

Cited by 49 publications

(25 citation statements)

References 8 publications

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“…It seems that the circulating levels of estrogens reached a peak within the period from 3 days prepartum to the day of parturition. This is almost the same observation as those made in cattle, which reach a plasma E 1 level peak in the last 4 days of pregnancy [26], and sheep, which reach a plasma E 1 level peak at parturition [27]. It has been suggested that the extra estrogen produced at parturition acts to contract the uterine muscle [28].…”

Section: Discussionsupporting

confidence: 67%

Excretion Patterns of Fecal Progestagens, Androgen and Estrogens During Pregnancy, Parturition and Postpartum in Okapi (Okapia johnstoni)

et al. 2007

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Abstract. The aim of the present study was to establish a simple method to monitor ovarian activity and non-invasively diagnose pregnancy in okapi (Okapia johnstoni). The feces of a female okapi were collected daily or every 3 days for 28 months. Steroids in lyophilized feces were extracted with 80% methanol, and the fecal levels of immunoreactive progestagens (progesterone and pregnanediolglucuronide), androgen (testosterone), and estrogens (estradiol-17β and estrone) were determined by enzyme immunoassays with commercially available antisera. Using the progesterone profiles, the durations of the luteal phase, follicular phase, and estrous cycle were determined to be 11.1 ± 0.4, 5.3 ± 0.6, and 16.5 ± 0.7 days (n=22), respectively. Fecal levels of immunoreactive progesterone, pregnanediol glucuronide, and testosterone gradually increased from early pregnancy and peaked several months before parturition. More pregnanediol glucuronide was excreted in feces than progesterone during late pregnancy, but not during the estrous cycle. Although the fecal concentrations of immunoreactive estradiol-17β and estrone change a little throughout pregnancy and non-pregnancy, they rose sharply and temporarily on the day following parturition. The present study indicates that fecal assays with commercial antisera for progesterone and pregnanediol glucuronide are useful for evaluating luteal activity and diagnosing pregnancy and indicates that estrogens might have some role as a trigger of parturition.

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Section: Discussionsupporting

confidence: 67%

Excretion Patterns of Fecal Progestagens, Androgen and Estrogens During Pregnancy, Parturition and Postpartum in Okapi (Okapia johnstoni)

et al. 2007

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“…All cows with spontaneous or induced parturition exhibited -if at all -only moderate increases of estrogens during the last week of gestation. This is clearly different from sheep, where an increased expression of CYP17 results in a distinct increase of free and sulfonated estrogens during the last few hours prior to parturition (Challis 1971, Tsang 1974. We cannot explain our observation but hypothesize that in the prepartal cow an increase in placental estrogen production following CYP17A1 upregulation is either masked by metabolism or excretion or -alternativelythat the prepartal upregulation of placental CYP17A1 may predominantly lead to the increased conversion of placental progesterone to its inactive 17a-hydroxylated metabolite, of which a further conversion on the D4-pathway to C19-steroids and estrogens in ruminants is very inefficient (Schuler et al 1994, Conley & Bird 1997.…”

Section: Initiation Of Parturition In Cattlementioning

confidence: 81%

“…The latter channels placental metabolism of pregnenolone into the D5-pathway resulting in a dramatic decrease in progesterone and an enhanced synthesis of estrogens. This switch in placental steroid production leads to an upregulation of contractionassociated proteins in the myometrium and the release of uterotonic prostaglandins in the uterus which eventually stimulates the onset of myometrial activity and expulsion of the fetus (Challis 1971, Tsang 1974, Mason et al 1989, Gyomorey et al 2000, Whittle et al 2000. Important steps of this signal cascade have been confirmed as occurring in late bovine gestation like the increase of fetal cortisol levels (Comline et al 1974, Hoffmann et al 1977, Hunter et al 1977 and the significant prepartal upregulation of CYP17 and COX2 in UTC (Schuler et al 2006a(Schuler et al , 2006b.…”

Section: Introductionmentioning

confidence: 99%

Investigations into the mechanisms controlling parturition in cattle

Shenavai

Preissing²,

Hoffmann³

et al. 2012

Reproduction

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A pronounced increase in fetal cortisol concentrations stimulating an increase in estrogen production at the expense of progesterone precursors in the placenta, luteolysis, and progesterone withdrawal is considered as a key event during the complex signal cascade leading to the initiation of parturition in cattle. However, there are many questions concerning the exact functional and/or temporal relationships between these individual processes which finally result in the expulsion of the calf and the timely release of the placenta. Thus, parturition was induced in 270-day pregnant cows using the progesterone receptor blocker aglepristone (group AG, nZ3), the prostaglandin F 2a analog cloprostenol (group PG, nZ4), and the glucocorticoid dexamethasone (group GC, nZ4) to characterize the effect on maternal steroid and prostaglandin levels and to identify immediate subsequent changes in placental morphology and gene expression as compared with untreated controls sampled on day 272 (group D272, nZ3) and cows during normal parturition (group NT, nZ4). All calves of the treatment groups were born on days 271-272, whereas gestational length in NT cows was 280.5G1.3 days. However, none of the treatments significantly induced the prepartal remodeling of placentomes characterized by a decline in trophoblast giant cells and reduction of the caruncular epithelium. Data on placental CYP17 and COX2 expression confirm that these key enzymes are upregulated by GC, whereas placental aromatase expression was not affected by any treatment. Maternal progesterone and prostaglandin profiles suggest differential effects of the treatments on luteal function and placental or uterine prostaglandin production. The results provide new information on the initiation of parturition in cattle but raise many new questions.

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“…In conclusion, E2S may be an important component of the mechanism for activating orexigenic, hypoxia responsiveness and neuroprotective pathways in the lamb as it approaches postnatal life. heart rate; estradiol; hypoxia; estrogen receptor; neuropeptides; neurosteroid IN FETAL SHEEP and pregnant ewes, sulfoconjugated estrogens are far more abundant than unconjugated estrogens (9,41,46). High concentrations of estrone sulfate in uterine vein plasma (compared to peripheral vein plasma) of pregnant sheep suggested a high secretion rate for this steroid by placenta in late gestation (15).…”

mentioning

confidence: 99%

“…IN FETAL SHEEP and pregnant ewes, sulfoconjugated estrogens are far more abundant than unconjugated estrogens (9,41,46). High concentrations of estrone sulfate in uterine vein plasma (compared to peripheral vein plasma) of pregnant sheep suggested a high secretion rate for this steroid by placenta in late gestation (15).…”

mentioning

confidence: 99%

Genomics of estradiol-3-sulfate action in the ovine fetal hypothalamus

Rabaglino

Richards

Denslow

et al. 2012

Physiological Genomics

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In fetal sheep during late gestation sulfoconjugated estrogens in plasma reach a concentration 40 -100 times greater than unconjugated estrogens. The objective of the present study was to determine the genomics of estradiol-3-sulfate (E2S) action in the ovine fetal brain. The hypothesis was that E2S stimulates genes involved in the neuroendocrine pathways that direct or facilitate fetal development at the end of gestation. Four sets of chronically catheterized ovine twin fetuses were studied (gestational age: 120 -127 days gestation) with one infused with E 2S intracerebroventricularly (1 mg/day) and the other remaining untreated (control). After euthanasia, mRNA samples were extracted from fetal brains. Only hypothalamic samples were employed for this study given the important function of this brain region in the control of the hypothalamus-pituitary-adrenal axis. Microarray analysis was performed following the Agilent protocol for one-color 8 ϫ 15 microarrays, designed for Ovis aries. A total of 363 known genes were significantly upregulated by the E 2S treatment (P Ͻ 0.05). Network and enrichment analyses were performed using the Cytoscape/Bingo software, and the results validated by quantitative realtime PCR. The main overrepresented biological processes resulting from this analysis were feeding behavior, hypoxia response, and transforming growth factor signaling. Notably, the genes involved in the feeding behavior (neuropeptide Y and agouti-related protein) were the most strongly induced by the E2S treatment. In conclusion, E2S may be an important component of the mechanism for activating orexigenic, hypoxia responsiveness and neuroprotective pathways in the lamb as it approaches postnatal life. heart rate; estradiol; hypoxia; estrogen receptor; neuropeptides; neurosteroid IN FETAL SHEEP and pregnant ewes, sulfoconjugated estrogens are far more abundant than unconjugated estrogens (9,41,46). High concentrations of estrone sulfate in uterine vein plasma (compared to peripheral vein plasma) of pregnant sheep suggested a high secretion rate for this steroid by placenta in late gestation (15). Plasma concentrations of estradiol-3-sulfate (E 2 S) are ϳ40 -100 times those of estradiol (E 2 ) in the lategestation fetal sheep. E 2 S is taken up by the fetal brain and stimulates responses that are both similar to and distinct from the responses to E 2 (43, 46). Sulfoconjugation increases the half-life in the blood (33) and supplies a ready source of E 2 in tissues (e.g., hypothalamus) that express steroid sulfatase (STS) (31, 43). E 2 S can bind estrogen receptor only after deconjugation by STS. We have proposed that, while the function of the sulfoconjugated estrogens in fetal and maternal sheep is unknown, deconjugation can increase estrogen action in specific tissues that express STS and estrogen receptor (43,44,46). The fetal brain expresses both STS and estrogen sulfotransferase (STF), allowing for the bidirectional interconversion of E 2 and E 2 S (31, 32), although the ratio of expression for these enzymes fa...

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Changes in plasma levels of estrone sulfate and estrone in the pregnant ewe around parturition

Cited by 49 publications

References 8 publications

Excretion Patterns of Fecal Progestagens, Androgen and Estrogens During Pregnancy, Parturition and Postpartum in Okapi (Okapia johnstoni)

Excretion Patterns of Fecal Progestagens, Androgen and Estrogens During Pregnancy, Parturition and Postpartum in Okapi (Okapia johnstoni)

Investigations into the mechanisms controlling parturition in cattle

Genomics of estradiol-3-sulfate action in the ovine fetal hypothalamus

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