Determination of progesterone and of free and conjugated estrogens in pregnant and pseudo-pregnant rats

doi:10.1016/0039-128X(74)90043-9

Steroids

Volume 24, Issue 1, July 1974, Pages 31-40

https://doi.org/10.1016/0039-128X(74)90043-9 Get rights and content

Abstract

Rat progesterone and estrogen levels have been determined in peripheral, ovarian, foetal plasma and in amniotic fluid, during estrous cycle, pseudo-pregnancy and pregnancy. From the progesterone levels, it was concluded that the predominant source of this hormone is the ovary. Though an ovarian contribution could not be excluded, placental origin of estrogens during pregnancy appeared evident. The estrogen levels showed the preponderance of the free form in a ratio E₂/E₁ < 1.

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Cited by (18)

The relation between pregnancy and stress in rats: Considering corticosterone level, hippocampal caspase-3 and MAPK activation
2011, European Journal of Obstetrics and Gynecology and Reproductive Biology
Citation Excerpt :
HPA axis activity is altered and basal corticosterone level up regulated [15]. Estrogen and progesterone levels rise [16] and the cardiovascular system is remodeled [17]. There is much to suggest that many of these changes should protect mother's brain from damages.
There are some evidences indicating that stress can affect hippocampal survival and function. During pregnancy mother is exposed to more stress and anxiety; also adrenal gland response to ACTH and glucocorticoid secretion is increased. Hence this study was done to assess the effect of restraint stress on corticosterone level, hippocampal caspase-3 and MAPK activation during pregnancy.
The restraint stress was applied in day 14 or days 14–20 (single and repeated stress) of rats’ pregnancy. The hippocampi were isolated after last stress episode and western blot analysis was done to assess caspase-3 and MAPK activation. Data were analyzed by one-way ANOVA followed by Student–Newman–Keuls for multiple comparison.
Our study showed that single and repeated stress both increase corticosterone level compared to non-stressed pregnant rats, but do not induce hippocampal apoptosis. Single stress increases transient JNK activation but not P38 and ERK. Repeated stress activated none of the MAPKs.
It seems that pregnancy protects mother's hippocampus against stress-induced damages.
Hydroxysteroid sulfotransferase activity in the rat brain and liver as a function of age and sex
1997, Steroids
The high concentrations of dehydroepiandrosterone sulfate and pregnenolone sulfate in the mammalian brain, despite the blood-brain barrier's impermeability to these compounds, and the apparent independence of these concentrations from those in plasma prompted us to investigate whether enzymatic sulfation of dehydroepiandrosterone was detectable in the rat brain. Low hydroxysteroid sulfotransferase activities were detectable in in vitro incubations of homogenates from all rat brain regions except the cerebellum, being highest in the hypothalamus and pons. This activity was not ascribable to enzyme in brain capillary blood. The activity was mainly cytosolic, although there was also significant activity in the partially purified nuclear fraction. The enzyme had different properties from those of hepatic isozymes, with a pH optimum of 6.5 and a high Km of approximately 2 mM for dehydroepiandrosterone. The enzyme was also active with pregnenolone as substrate. Activities in the brain were approximately 300-fold lower than in the liver but, as in the liver, these were higher in females than in males. The variations in brain activity as a function of age did not parallel those in the liver. Relatively high activities were found in the fetal brain and declined at birth, while activities were insignificant in the fetal liver and rose following birth. There was a major peak in activity in pubertal female brains, but this peak was less important, and later, in males. No evidence was found to indicate that the low brain enzyme activities and high Km were attributable either to the presence of an inhibitor or to the steroid sulfation actually being a secondary activity of another brain sulfotransferase. We discuss whether the sulfotransferase activities found are adequate to synthesize the dehydroepiandrosterone and pregnenolone sulfate found in brain.
Estrogen-binding properties of rat serum α<inf>1</inf>-fetoprotein and its isoforms. Investigation of the apparent non-integrality of sites on the unfractionated protein
1990, Journal of Steroid Biochemistry
Rat fetal serum α₁-fetoprotein (AFP), a heterogeneous glycoprotein, binds estrogens with high affinity but at a fractional number of sites even after treatment with charcoal (n = 0.6), which may mean 60% of the protein has 1 site and the remainder none. To investigate the origin of this fractional number of sites the “native” protein (purified by negative affinity chromatography) was further purified (step 1) and fractionated (step 2) into its two main charge variants (electrophoretically “slow” and “fast”) by a two-step fast-protein liquid chromatography method. The binding parameters for estrone and estradiol-17β of the “native” and “repurified” proteins and of each charge variant were determined by equilibrium microdialysis. The molar extinction coefficient at 278 nm of each sample was also determined. (1) The “repurified” AFP and each charge variant had a number of binding sites for estrogens close to unity. This increase in the number of sites could neither be explained by the loss of a non-binding isoform (corresponding to 40% of the protein) during chromatography, nor by the existence of complex negative modulatory interactions between isoforms.
1. 1.
  (2) The affinities for estrogens of the “repurified” protein and the two charge variants were slightly decreased compared to that of “native” AFP, except that the “fast” form had the “native” protein's high affinity for estrone—but not for estradiol-17β.
2. 2.
  (3) The molar extinction coefficients at 278 nm of the “repurified” AFP and the isoforms were much lower than that of the “native” protein.
These results suggest that the presence of (an) inhibitor(s) of estrogen binding on the “native” protein which is/are removed by the ion-exchange fast protein liquid chromatography (FPLC) column. A ligand absorbing at 278 nm, which may or may not be the inhibitor, is also removed. The isoform heterogeneity with respect to estrone binding is discussed.
Ontogeny of Steroid Receptors in the Reproductive System
1986, International Review of Cytology
Steroid hormones play an important role during the crucial periods of gestation—namely, conception, nidation, embryonic development, and fetal maturation. Progesterone and the estrogens are two of the steroid hormones that play a basic role in pregnancy. During the course of normal pregnancy, the production rates and plasma concentrations of these steroid hormones can vary significantly, sometimes increasing 100-300 times at the end of gestation, as in the case of estrogens and progesterone in pregnant women. Also during gestation, the production of various steroid hormones is the contribution of the secretion of three compartments: maternal, placental, and fetal. This production is different in the three compartments, both qualitatively and quantitatively, and also depends on the period of pregnancy as well as the species considered. The placenta makes most of the progesterone and estrogens produced during pregnancy. This chapter discusses various aspects of hormone action such as the presence of steroid hormone receptors in the fetal and placental compartments and the correlation of these receptors with biological effects during fetal development and in newborns. The presence of steroid receptors in different fetal tissues confirms that the mechanism of action can be similar to that postulated in target organs after birth. Good correlation exists among receptor binding, nuclear translocation, and biological responses elicited by the hormone in the fetus and the newborn.
Testosterone, dihydrotestosterone and estradiol-17β levels in maternal and fetal plasma and in fetal testes in the rat
1984, Journal of Steroid Biochemistry
In Sherman rats testosterone, dihydrotestosterone (DHT) and estradiol-17β levels were measured in maternal and fetal plasma of both sexes during the last 5 days of gestation and in the fetal testes from day 14.5 of pregnancy using celite microcolumn chromatography and radioimmunoassay. All the plasma testosterone concentrations in males were at least 4 times higher than in their female littermates. In male fetuses, levels of plasma testosterone were maximum on day 18.5 (mean = 1.42 ng/ml) and declined thereafter (mean = 0.85 ng/ml on day 21.5). In female fetuses and in mothers, levels were consistently very low (mean < 0.2 ng/ml). Plasma DHT titers in fetal plasma of the two sexes and in maternal plasma were consistently minute. Plasma estradiol-17β levels in fetuses did not differ between sexes; they were higher than maternal levels; there was a prepartum increase both in fetuses and their mothers. Testicular testosterone content became detectable on day 15.5, increased to reach a peak on day 18.5 (mean = 2.3 ng/testis) and remained at this plateau throughout the end of gestation. Intratesticular DHT and estradiol-17β were in minute concentrations. From these data we conclude that, in fetal rat, (1) DHT in genital tract is entirely formed in situ during masculinization, (2) among the three plasma steroids assayed, only testosterone can play a determining role in sexual differentiation.
A kinetic study of rat liver 17β-hydroxysteroid-dehydrogenase
1979, Biochimie

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^☆: This work was supported by CNRS grant.

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Determination of progesterone and of free and conjugated estrogens in pregnant and pseudo-pregnant rats☆

Abstract

Acta Endocr.

Endocr.

Endocr.

J. Reprod. Fert.

C.R. Acad. Sc. Paris

C.R. Acad. Sc. Paris