Androstenedione, Testosterone, and Estradiol Concentrations in Fetal and Maternal Plasma in Late Pregnancy in the Sheep*

Yu, Han; Cabalum, T.; Jansen, C.A.M.; Buster, John E.; Nathanielsz, Peter W.

doi:10.1210/endo-113-6-2216

Cited by 33 publications

(18 citation statements)

References 10 publications

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“…However, none of these studies reported the estradiol concentration achieved in maternal or fetal plasma at the dose of estradiol used in their studies. In a pilot study, we found that infusion of estradiol at a rate of 2 mg/d only raised fetal or maternal plasma estradiol up to 20 -25 pg/ml (data not shown), well below the level observed in maternal plasma at spontaneous labor (10,24,25). At the dosage used in the present study, we were able to produce maternal plasma estradiol concentrations of about 350 pg/ml (Fig.…”

Section: Discussioncontrasting

confidence: 42%

Prostaglandin Mediates Premature Delivery in Pregnant Sheep Induced by Estradiol at 121 Days of Gestational Age

et al. 2004

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The experiments reported here were designed for both in vivo and in vitro approaches in the same animals to obtain a better picture of the role of estrogen in the control of parturition. Chronically catheterized pregnant ewes were treated with vehicle (n = 5) or estradiol (n = 6), 5 mg twice a day, im for 2 d starting at d 119 of gestation. Maternal and fetal plasma estradiol, progesterone, and cortisol were measured by RIA and maternal plasma prostaglandin (PG) F2alpha was measured by enzyme immunoassay. Intrauterine PG H synthase 2 mRNA and protein and placental P450(c17)alpha hydroxylase mRNA were determined by Northern, in situ hybridization, Western blot analysis, and immunocytochemistry. Data were analyzed by ANOVA. Five of six estradiol-treated ewes delivered their fetuses within 48 h; however, the placenta was still retained 5-6 h after fetal delivery. Both maternal plasma estradiol and PGF2 alpha increased significantly in the estradiol-treated group. Maternal and fetal plasma progesterone and cortisol were not altered in either group. There were significant increases of PGH synthase 2 mRNA and protein in myometrium, endometrium, and maternal placenta but not in fetal placenta in estradiol-treated ewes. Placental P450(c17)alpha hydroxylase mRNA was not detectable in vehicle or estradiol-treated groups. Estradiol can, in the absence of increase in plasma cortisol, stimulate uterine PG production and induce labor, resulting in fetal delivery in the sheep. Failure of placental delivery after estradiol treatment suggests that estradiol alone is insufficient to stimulate some of the key changes required to complete delivery at the stage of gestation studied.

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Section: Discussioncontrasting

confidence: 42%

Prostaglandin Mediates Premature Delivery in Pregnant Sheep Induced by Estradiol at 121 Days of Gestational Age

et al. 2004

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“…Conversely estradiol concentrations are similar between male and female rat fetuses (239), and exceed the maternal concentration (146,239). In fetal lambs, testosterone and estradiol exceeded the maternal concentration at all time points (117,650,757).…”

Section: Sex Steroidsmentioning

confidence: 86%

Bone Development and Mineral Homeostasis in the Fetus and Neonate: Roles of the Calciotropic and Phosphotropic Hormones

Kovacs

2014

Physiological Reviews

211

188

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Mineral and bone metabolism are regulated differently in utero compared with the adult. The fetal kidneys, intestines, and skeleton are not dominant sources of mineral supply for the fetus. Instead, the placenta meets the fetal need for mineral by actively transporting calcium, phosphorus, and magnesium from the maternal circulation. These minerals are maintained in the fetal circulation at higher concentrations than in the mother and normal adult, and such high levels appear necessary for the developing skeleton to accrete a normal amount of mineral by term. Parathyroid hormone (PTH) and calcitriol circulate at low concentrations in the fetal circulation. Fetal bone development and the regulation of serum minerals are critically dependent on PTH and PTH-related protein, but not vitamin D/calcitriol, fibroblast growth factor-23, calcitonin, or the sex steroids. After birth, the serum calcium falls and phosphorus rises before gradually reaching adult values over the subsequent 24 -48 h. The intestines are the main source of mineral for the neonate, while the kidneys reabsorb mineral, and bone turnover contributes mineral to the circulation. This switch in the regulation of mineral homeostasis is triggered by loss of the placenta and a postnatal fall in serum calcium, and is followed in sequence by a rise in PTH and then an increase in calcitriol. Intestinal calcium absorption is initially a passive process facilitated by lactose, but later becomes active and calcitriol-dependent. However, calcitriol's role can be bypassed by increasing the calcium content of the diet, or by parenteral administration of calcium.

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“…However, the percentage of LH cells remained stable at that time, suggesting that a "dilution" of gonadotropes in other pituitary cells is not the main factor involved in this decrease. At the same period, there is a decline in plasma LH and FSH levels [28], most probably due to the rise in fetoplacental sex steroids and perhaps to an anti-gonadotropic action of PRL [34][35][36]. Since these hormones are able to inhibit directly or indirectly [37][38][39][40] the synthesis of LH and/or FSH, the decrease in the percentage of FSH cells observed at this moment could also be due to cells' becoming undetectable because of the small amounts of gonadotrope hormones they contain.…”

Section: Discussionmentioning

confidence: 99%

Heterogeneity in the Storage of Gonadotropins in the Ovine Fetus and Evidence for Luteinizing Hormone-Follicle-Stimulating Hormone Cells in the Fetal Pituitary

Messaoud-Toumi¹,

Taragnat²,

Durand³

1993

Biology of Reproduction

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In this immunocytochemical study, heterogeneity in the storage of gonadotropins in the sheep fetus was investigated. LH cells were first detected at 50 days of gestation, whereas FSH and LH-FSH cells were observed from Day 89 on; no gonadotropes containing ACTH were observed. LH cell percentage increased for both sexes between 99 and 120 days of gestation (from 2.8 +/- 0.1 to 4.0 +/- 0.3), remained high until term, and did not change after birth. In males, FSH cell percentages increased about twofold between 120 and 130 days to 4.0 +/- 0.4, fell at 140 days to 1.6 +/- 0.1, and then increased in the newborn lambs about twofold. A similar pattern of development was observed in females, but the percentages were lower than in males. LH-FSH cell percentages increased about twofold in males between 99 and 120 days of gestation to 1.1 +/- 0.1, decreased to 0.8 +/- 0.1 at 140 days, then increased about twofold in newborn lambs. In the 99-day-old females, this percentage was 0.5 +/- 0.1; it remained stable between 99 days of fetal life and term and did not change after birth. Hence, the pattern of change in the percentages of these cells appeared to be similar to that of LH cells and different from that of FSH cells. This suggests that LH-FSH cells might result from a shift of monohormonal cells to bihormonal cells. However, these cells seem to be regulated differently in male and female fetuses, and this suggests that they possess a specific role during ontogenesis.

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Androstenedione, Testosterone, and Estradiol Concentrations in Fetal and Maternal Plasma in Late Pregnancy in the Sheep*

Cited by 33 publications

References 10 publications

Prostaglandin Mediates Premature Delivery in Pregnant Sheep Induced by Estradiol at 121 Days of Gestational Age

Prostaglandin Mediates Premature Delivery in Pregnant Sheep Induced by Estradiol at 121 Days of Gestational Age

Bone Development and Mineral Homeostasis in the Fetus and Neonate: Roles of the Calciotropic and Phosphotropic Hormones

Heterogeneity in the Storage of Gonadotropins in the Ovine Fetus and Evidence for Luteinizing Hormone-Follicle-Stimulating Hormone Cells in the Fetal Pituitary

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