Role of OAT4 in Uptake of Estriol Precursor 16α-Hydroxydehydroepiandrosterone Sulfate Into Human Placental Syncytiotrophoblasts From Fetus

Estriol biosynthesis in human placenta requires the uptake of a fetal liver-derived estriol precursor, 16α-hydroxydehydroepiandrosterone sulfate (16α-OH DHEAS), by placental syncytiotrophoblasts at their basal plasma membrane (BM), which faces the fetal circulation. The aim of this work is to identify the transporter(s) mediating 16α-OH DHEAS uptake at the fetal side of syncytiotrophoblasts by using human placental BM-enriched vesicles and to examine the contribution of the putative transporter to estriol synthesis at the cellular level, using choriocarcinoma JEG-3 cells. Organic anion transporter (OAT)-4 and organic anion transporting polypeptide 2B1 proteins were enriched in human placental BM vesicles compared with crude membrane fraction. Uptake of [(3)H]16α-OH DHEAS by BM vesicles was partially inhibited in the absence of sodium but was significantly increased in the absence of chloride and after preloading glutarate. Uptake of [(3)H]16α-OH DHEAS by BM vesicles was significantly inhibited by OAT4 substrates such as dehydroepiandrosterone sulfate, estrone-3-sulfate, and bromosulfophthalein but not by cyclosporin A, tetraethylammonium, p-aminohippuric acid, or cimetidine. These characteristics of vesicular [(3)H]16α-OH DHEAS uptake are in good agreement with those of human OAT4-transfected COS-7 cells as well as forskolin-differentiated JEG-3 cells. Estriol secretion from differentiated JEG-3 cells was detected when the cells were incubated with 16α-OH DHEAS for 8 hours but was inhibited in the presence of 50 μM bromosulfophthalein. Our results indicate that OAT4 at the BM of human placental syncytiotrophoblasts plays a predominant role in the uptake of 16α-OH DHEAS for placental estriol synthesis.

[Effect of Escherichia coli secreted metabolites on functional activity of human neutrophils against the background of estriol effect]

AIM

Study the effect of Escherichia coli acellular metabolites of various phases of development on phagocytic activity of neutrophils against the background of pregnancy hormone effect--estriol (E3).

MATERIALS AND METHODS

E. coli K12 (wt) metabolites were selected at the end of adaptation and logarithmic growth phases by filtration after cultivation at 37 degrees C in LB broth. Neutrophils of heparinized venous blood of healthy non-pregnant women (follicular phase, n = 8) were incubated for 1 hour with E3 at 2 ng/ml and 20 ng/ml, then 30 minutes with E. coli metabolites, LB medium or Hanks' solution at 37 degrees C. Phagocytic activity evaluation was carried out by inhibition of bioluminescence of E. coli K12 TG1 lux+.

RESULTS

Exometabolites of logarithmic growth phase of E. coli culture inhibited neutrophil phagocytosis after 40 - 60 minutes of incubation in contrast to metabolites of adaptation phase compared with LB medium. Neutrophil cultivation after hormone treatment in LB medium that has the ability to stimulate neutrophil phagocytosis compared with Hanks' solution did not alter their phagocytic activity. However inhibiting effect of E3 at 20 ng/ml on neutrophil phagocytosis compared with control was exhibited in Hanks' solution (at 50 - 60 minutes) and after the effect of E. coli adaptation phase metabolites (at 40 - 60 minutes).

CONCLUSION

E3 at the level extrapolated from its level at III trimester of pregnancy could facilitate the reduction of antimicrobial potential of neutrophils at the early stages of growth of pathogenic microorganisms.

Aromatase inhibition by 4 beta,5 beta-epoxides of 16 alpha-hydroxyandrostenedione and its 19-oxygenated analogs, potential precursors of estriol production in the feto-placental unit

To gain insight into the nature of the substrate binding site and the catalytic function of aromatase, we studied the inhibition of androstenedione aromatization by 4beta,5beta-epoxy-16alpha-hydroxyandrostenedione (4) and its 19-hydroxy and 19-oxo derivatives, 5 and 6, as well as the biochemical aromatization of these steroids in human placental microsomes. The 19-methyl and 19-oxo compounds, 4 and 6, were weak competitive inhibitors of aromatase, with apparent K(i) values of 246 microM and 270 microM, respectively, whereas the 19-hydroxy compound 5 inhibited aromatase in a non-competitive manner with the K(i) of 135 microM. The 19-methyl compound 4 inactivated aromatase in a time-dependent manner with k(inact) of 0.213 min(-1) in the presence of NADPH in air, but the other two did not cause it. The conversion of the three epoxides into estrogen, as well as 19-oxygenation of 19-methyl steroid 4 with human placental microsomes in the presence of NADPH in air, were not detected by gas chromatography-mass spectrometry. The present results are consistent with the two binding sites theory in the active site of aromatase.

Changes in rates of salivary estriol increases before parturition at term

OBJECTIVE

The aim of this study was to characterize the increases of salivary estriol concentrations before the onset of labor at term.

STUDY DESIGN

Salivary estriol concentrations were measured in weekly patient-collected samples by means of a sensitive (mean +/- SD threshold, 0.025 +/- 0.001 ng/mL; coefficient of variation, 3.8%) direct enzyme immunoassay in a microtiter plate format. The salivary estriol concentrations in 16 healthy pregnant women were characterized from 30 weeks' gestation until the time of parturition and delivery. Samples were stored frozen at collection and analyzed in batches after delivery.

RESULTS

The median salivary estriol concentration profile revealed a nonlinear rise beginning from 30 weeks' gestation (0.89 ng/mL) until term (2.70 ng/mL, an increase of 201%). At 35 weeks' gestation the salivary estriol concentration median value increased sharply (positive inflection point, 50%-93% increase) at a demarcation between a slower increase during early pregnancy and a more rapid increase during late pregnancy. This positive inflection point associated with a late pregnancy increase characterized subgroups of pregnancies according to the lengths of gestation as follows: early term (delivered at <38 weeks 1 day's gestation), middle term (delivered at 38 weeks 1 day-40 weeks' gestation), and late term (delivered at >40 weeks' gestation). Five weeks before delivery the mean (+/-SEM) rate of rise in salivary estriol concentration was 0.50 +/- 0.13 ng/mL per week to 0.84 +/- 0.26 ng/mL per week in the early term group. The increase in rate for the middle term group was 0.32 +/- 0.06 ng/mL per week to 0.37 +/- 0.26 ng/mL per week, whereas in the late term group the rate of salivary estriol concentration rise was 0.37 +/- 0.03 ng/mL per week to -0.03 +/- 0.25 ng/mL per week.

CONCLUSION

These data demonstrate in normal pregnancies (1) that a direct, nonradiometric measure of salivary estriol concentration can be used to monitor the late pregnancy increase in estriol production, (2) that 35 weeks' gestation marks a positive inflection point of the onset of increased estriol production, and (3) that the late pregnancy rise in salivary estriol concentration shows distinct patterns that tend to be characteristic of the length of pregnancy. These data support the concept that the rate of increase of estriol production is related to the timing of the onset of labor.

Placental synthesis of oestriol in Down's syndrome pregnancies

In the second trimester, oestriol is synthesized in the placenta and secreted into the maternal circulation. 16alpha-hydroxy dehydroepiandrosterone sulphate (16alpha-OH-DHEAS) is formed in the fetal liver by hydroxylation of dehydroepiandrosterone sulphate (DHEAS) and transported to the placenta where it undergoes desulphation by steroid sulphatase (STS) and aromatization to oestriol. Maternal serum levels of unconjugated oestriol (UE3) are lower in Down's syndrome pregnancies than in unaffected pregnancies in the second trimester. The underlying cause of this variation was investigated in placenta, fetal liver, maternal serum and amniotic fluid from Down's syndrome pregnancies by measuring the levels of UE3, DHEAS and STS in appropriate tissues and in corresponding samples from unaffected pregnancies. UE3 levels, expressed as multiples of the control median at the appropriate gestation (MOM), were lower in placental tissue (0.52 MOM), maternal serum (0.65 MOM) and amniotic fluid (0.61 MOM) than in unaffected pregnancies. There was a significant correlation between placental and maternal serum levels of UE3 in the Down's syndrome cases. The median STS activity in placental tissue from Down's syndrome pregnancies (1.14 MOM) was not significantly different from that of the control pregnancies (1. 01 MOM), suggesting that placental turnover of the fetal precursor DHEAS is not reduced. However, levels of DHEAS were reduced in maternal serum (0.69 MOM), placental tissue (0.54 MOM) and fetal liver (0.65 MOM) from Down's syndrome pregnancies. Thus, a diminished supply of the fetal precursor DHEAS may be the cause of the decreased placental production of UE3 in Down's syndrome pregnancies in the second trimester.

Urinary analyte screening: a noninvasive detection method for Down syndrome?

Prenatal screening for Down syndrome using maternal serum markers achieves detection rates of 60-80% with a 5% false positive rate. Improvement in the accuracy of screening, as well as its ease and safety, will increase the use of such tests. The most effective of the current serum markers is human chorionic gonadotropin (hCG). Studies on beta core fragment (beta CF), the major urinary metabolite of hCG, have indicated that screening with beta CF and other markers measured in maternal urine might improve the detection of Down syndrome and provide a less expensive and simpler test. However, recent results have been unusually variable. Although it has great potential, the true clinical value of maternal urine screening to detect Down syndrome still remains to be determined.

Steroid sulphatase deficiency is the major cause of extremely low oestriol production at mid-pregnancy: a urinary steroid assay for the discrimination of steroid sulphatase deficiency from other causes

A method for determining whether a pregnant woman with an extremely low serum oestriol (ELSE) measurement of mid-trimester is carrying a fetus with steroid sulphatase deficiency or another more serious disorder is described. We undertook GC/MS analysis of steroids in random maternal urine samples and quantified oestriol, oestriol precursors (dehydroepiandrosterone (DHEA), 5-androstene-3 beta, 17 beta-diol, 16 alpha-hydroxy-dehydroepiandrosterone and 5-androstene-3 beta, 16 alpha, 17 beta-triol), pregnanediol, and five other steroids largely unaffected by pregnancy (androsterone, etiocholanolone, tetrahydrocortisol, 5 alpha-tetrahydrocortisol and tetrahydrocortisone). Thirty-two samples collected from seven normal pregnant women between the 7th and 27th week of pregnancy and 22 from individuals with ELSE were analysed. Diagnostic ratios of excreted products were developed. These included ratios of oestriol and oestriol precursors to the cumulative value for the five non-pregnancy-related steroids and ratios of oestriol and oestriol precursors to pregnanediol and to each other. Our data demonstrated high 3 beta-hydroxy-5-ene steroid excretion in all ELSE patients together with low urinary oestriol excretion, a situation only consistent with deficiency of steroid sulphatase. The normal individuals had high oestriol and low excretion of oestriol precursors. No patient in our series showed the low oestriol levels and low oestriol precursor values that would indicate a fetal adrenal abnormality as the underlying defect.

Why so much oestriol? A comparison of the aromatisation of androstenedione and 16 alpha-hydroxyandrostenedione when incubated alone or together with human placental microsomes

Estimates of the relative abundance of 16 alpha-hydroxy- and 16-deoxyoestrogens in late pregnancy urine lie between 13:1 and 5:1, yet the ratio of the concentrations of the major precursors 16 alpha-hydroxydehydroepiandrosterone sulphate and dehydroepiandrosterone sulphate in cord blood is about 2.5:1. This discrepancy might imply that 16 alpha-hydroxy-C19 steroids are used more efficiently for placental oestrogen biosynthesis than are the 16 alpha-deoxy-C19 steroids. On testing this hypothesis by incubation of placental microsomes with 16 alpha-hydroxy- and 16-deoxy- precursors together (concentration ratios 128:1 to 1:1), initial rates of oestrogen formation were highest from the 16-deoxy-C19 steroid. Additionally, whilst each substrate appeared to inhibit the aromatisation of the other, the 16-deoxy-C19 steroid was the more potent inhibitor. These findings were supported by an analogous experiment with placental slices. When each precursor was examined separately with microsomes from 4 placentae, aromatisation of the 16 alpha-hydroxy-C19 steroid (Michaelis constant, (Km) 0.75-1.24 mumol/l, maximum reaction velocity (Vmax) 28-69 pmol product/min/mg protein) was less efficient than that of the 16-deoxy-C19 steroid (Km 0.10-0.15 mumol/l, Vmax 71-145 pmol product/min/mg protein). To reconcile the disparity between the measured utilisation of precursors in vitro and expectations drawn from precursor availability and urinary excretion rates, sources of urinary 16 alpha-hydroxyoestrogens additional to placental aromatisation need to be considered. Hydroxylation of 16-deoxyoestrogens (the phenolic pathway) appears limited but aromatisation in fetal liver of 16 alpha-hydroxyandrostenedione not utilised by the placenta appears to be worth attention.

Synthesis of 16 alpha-hydroxyandrost-4-ene-3,17,19-trione and 3 beta, 16 alpha-dihydroxyandrost-5-ene-17,19-dione; potential intermediates of estriol biosynthesis

16 alpha-Hydroxyandrost-4-ene-3,17,19-trione (10) was synthesized from the 16 alpha-hydroxy-6 beta,19-epoxy-17-one 3 via protection of the 16 alpha-hydroxy function as its tert-butyldimethylsilyl ether or acetate. Reductive cleavage of the epoxy ring of the silyl ether 4 or the acetate 5 with zinc dust gave the 19-alcohol 6 or 7, which was treated with pyridinium dichromate or Jones reagent, respectively, and then hydrolyzed with diluted sulfuric acid, yielding the desired steroid 10. 3 beta,16 alpha-Dihydroxyandrost-5-ene-17,19-dione (14) was also synthesized from 5 alpha-bromo-3 beta,16 alpha-diacetoxy-6 beta, 19-epoxyandrostan-17-one (11) through the intermediates 12 and 13 with the 3 beta- and 16 alpha-hydroxy functions protected as their acetates in a reaction sequence similar to that above.

Conversion to estriol in "normal", benign and malignant human breast tissues

Since there are controversial reports in the literature on 16 alpha-hydroxylase activity in human breast tumors, we have studied this enzyme activity in "normal", benign and malignant breast tissues by measuring the conversion of estradiol to estriol. Whereas 8 out of 14 (58%) malignant tumors showed positive activity, none of the other tissues had any detectable 16 alpha-hydroxylase activity. These preliminary results, when combined with reports in the literature on animal and human tissues, appear to indicate that more extensive studies on this enzyme could be useful as it could be an additional metabolic marker in human breast cancer.

Evidence for separate sites for aromatisation of androstenedione and 16 alpha-hydroxyandrostenedione in human placental microsomes

Much greater quantities of 16 alpha-hydroxyoestrogens (e.g. oestriol) than of 16-deoxyoestrogens (e.g. oestradiol-17 beta) are formed in human pregnancy than might be expected from the relative availability to the placenta of the 16 alpha-hydroxy- and 16-deoxy-C19 precursors. To investigate this further, 16 alpha-hydroxyandrostenedione (16 alpha-OH-A4) and androstenedione (A4) were tested in vitro as substrates and mutual inhibitors of human placental aromatase. It was found that the Km for aromatisation of A4 (mean = 0.26 mumol/l) was very similar to Ki (0.30, 0.35 mumol/l) for the inhibition by A4 of the aromatisation of 16 alpha-OH-A4. Similarly, Km for aromatisation of 16 alpha-OH-A4 (mean = 1.21 mumol/l) had the same value as the Ki (1.0, 1.2 mumol/l) for the inhibition by 16 alpha-OH-A4 of the aromatisation of A4. From graphical analysis of Lineweaver-Burk plots, both inhibitions were characterised as noncompetitive. Hence, it was concluded that the two 16-deoxy- and 16-hydroxy-C19 substrates bind at separate, but interactive, sites and that each substrate on binding inhibits the aromatisation of the other. Additional evidence for the separate but interactive substrate binding sites for the 16-deoxy- and 16-hydroxy-C19 steroids was obtained by use of the suicide inhibitor 4-hydroxyandrostenedione (4-OH-A4), which is recognised as binding to the aromatisation site for A4. Aromatisation of 16 alpha-OH-A4 was found to be inhibited by pre-incubation of the microsomes with 4-OH-A4 (0.1 mumol/l). The presence of A4 (4.6 mumol/l), but not of 16 alpha-OH-A4 (4.0 mumol/l) during the pre-incubation successfully protected the subsequent aromatisation of 16 alpha-OH-A4 from this inhibition. In addition, the Km values, reported here, suggest also that the 16-deoxyandrogens are preferred to the 16 alpha-hydroxyandrogens as oestrogen precursors. In consequence, factors other than substrate affinity and plasma concentrations must be presumed to be involved in the overwhelming production of 16 alpha-hydroxyoestrogens in human pregnancy.

Quantification of the sulfates of 16 alpha-hydroxy androgens that are possible precursors of estriol-3-sulfate in human breast cyst fluid

The concentration of 16 alpha-hydroxydehydroepiandrosterone-3-sulfate (16 alpha-OHDHAS) was determined in 29 samples of human breast cyst fluid (BCF) and in 15 of these, androst-5-ene-3 beta,16 alpha,17 beta-triol-3-sulfate (A-TriolS) was also assayed. The median value of both was about 100 ng/mL and the ranges were from 1.4 to about 1800 ng/mL. There was a significant association in the values for the two sulfates (p less than 0.05). These concentrations are consistent with a role for 16 alpha-hydroxy androgens as possible precursors for estriol-3-sulfate. The latter is highly elevated relative to other body fluids in BCF. The androgens also correlated directly with the concentrations of K+, an indicator of apocrine proliferation of breast cysts.

[Synthesis and metabolism of estriol conjugates]

As an indicator of fetal well being, the urinary estriol value is widely utilized. But the discrepancy between the results of NST and urinary estriol value has recently been pointed out. The estimation of plasma estriol is also recommended as a more reliable means of fetal assessment than that of urinary estriol. The purpose of the study is to clarify the patterns of estriol conjugates in maternal blood, retroplacental blood and cord blood, and further to elucidate the metabolism and secretion of each conjugate in organs and to determine the most useful conjugate as a source of fetal information. In normal pregnancy urine, estriol glucosiduronate is the dominant component of urinary estriol. In preeclampsia, the percentage of G decreased and that of G-S increased. In retroplacental blood, G-S is the main conjugate. On the other hand in cord blood, S is the dominant conjugate. The placental perfusion experiment revealed that the placenta hydrolyzed each conjugate to a free form and did not convert one conjugate to another. Periodical determination of plasma estriol conjugates in pregnant women revealed that the G-S fraction fluctuated most during parturition. The importance of liver as a possible site for estriol conjugation and the role of kidney in selective clearance of estriol conjugates are discussed.

Competitive studies with dehydroepiandrosterone sulfate and 16 alpha-hydroxydehydroepiandrosterone sulfate in cultured human choriocarcinoma JEG-3 cells: effect on estrone, 17 beta-estradiol, and estriol secretion

The estradiol (E2) to estriol (E3) ratio during human pregnancy depends on fetal liver hydroxylation of fetal adrenal dehydroepiandrosterone sulfate (DHEAS) and conversion by the trophoblast of DHEAS and 16 alpha-hydroxy-DHEAS (16 OH-DHEAS) to estrone (E1), estradiol (E2), and estriol (E3), respectively. It is not known whether the conversion of DHEAS into E1 and E2 influence the conversion of 16OH-DHEAS into E3 and vice versa. To examine this question, we studied these interactions in human choriocarcinoma JEG-3 cells. In serum-free medium (Dulbecco's Modified Eagle's Medium), JEG-3 cells secreted hCG [27 +/- 3 (+/- SEM) ng/mg cellular protein X 24 h] and progesterone (22 +/- 2.5), but neither C-19 nor C-18 steroids. The addition of DHEAS resulted in secretion of E1 and E2; at a concentration of 500 ng DHEAS/ml, the secretion of E1 (1 +/- 0.16) and E2 (11 +/- 3.1) was maximal, while E3 remained undetectable. The addition of 1000 ng 16 OH-DHEAS/ml resulted in maximum E3 secretion (13 +/- 1.8), while E1 and E2 remained undetectable. The addition of increasing concentrations of DHEAS to cultures exposed to 1000 ng 16OH-DHEAS/ml caused a decrease in E3 secretion and increased secretion of E1 and E2. Conversely, addition of increasing concentrations of 16OH-DHEAS in cultures exposed to 500 ng DHEAS/ml resulted in inhibition of E1 and E2 secretion and increased E3 secretion. A concentration of 16OH-DHEAS that inhibited the conversion of DHEAS into E1 and E2 neither altered the intracellular to extracellular steroid ratios (approximately 0.1) nor reduced the secretion of DHEA, androstenedione, and testosterone. The inhibitory effect of 16OH-DHEAS was minimal at low DHEAS concentrations (favoring the secretion of E1 and E2) and was greatly enhanced at concentrations of DHEAS that induced maximum E1 and E2 secretions. The results indicate that in trophoblastic cells, the metabolism of DHEAS can modulate E3 secretion, and the metabolism of 16OH-DHEAS can modulate the secretion of E1 and E2; and this regulatory mechanism appears to take place at the level of the aromatase system.

Current concepts in management of obstetric problems for pediatricians. I. Monitoring the high-risk fetus

Modern pediatric/neonatal practice demands an understanding of fetal monitoring. Biochemical techniques have given way to biophysical and ultrasonographic modalities in an attempt to improve both sensitivity and specificity. Simple techniques such as fetal movement counts show promise and are being investigated.

High-performance liquid chromatographic determination of aromatization of 16 alpha-hydroxylated androgens with human placental microsomes

A sensitive nonradiometric assay of aromatization of 16 alpha-hydroxylated androgens, 16 alpha-hydroxy-4-androstene-3,17-dione (16 alpha-OHA), and 16 alpha-hydroxytestosterone (16 alpha-OHT), has been developed using reverse-phase high-performance liquid chromatography with voltametric detector. The estrogens produced by human placental microsomes, estriol (E3) and 16 alpha-hydroxyestrone (16 alpha-OHE1), were simultaneously detected in quantities as low as 1-2 ng using 3-methoxy-1,3,5(10)-estratriene-2, 16 alpha,17 beta-triol as an internal standard. E3 was the only estrogen detected from the incubate of 16 alpha-OHT with the microsomes and NADPH, while 16 alpha-OHA gave 16 alpha-OHE1 and E3 under the same conditions. Apparent Km and Vmax of the microsomal aromatase for 16 alpha-OHA and 16 alpha-OHT were 2.56 microM and 71.4 pmol/min/mg and 13.33 microM and 15.4 pmol/min/mg, respectively.

[3H]Oestradiol metabolism by 18-day rat interstitial cells in culture and the effect of FSH: presence of 16 alpha-hydroxylase

The metabolism of [3H]oestradiol by interstitial cells in culture prepared from 18-day old rat testes was investigated. Interstitial cells were able to convert [3H]oestradiol to [3H]oestriol as confirmed by recrystallization of oestriol to constant specific activity from samples containing cells and not from controls. This demonstrated for the first time the presence of 16 alpha-hydroxylase in rat testicular interstitial cells. The effect of in vitro FSH treatment on the cells in culture was also investigated. FSH failed to affect 16 alpha-hydroxylase activity since we could not demonstrate a significant difference between treated and untreated preparations. The 16 alpha-hydroxylation of phenolic steroids is widely regarded as the major pathway of oestrogen metabolism in mammals. This metabolic step significantly reduces the biological activity of oestradiol. The presence of 16 alpha-hydroxylase in interstitial cells suggests that it may play a role in inactivating the oestradiol that is produced in the Leydig cells and thus prevent its intracellular accumulation. Such activity may conceivably play a role in the overall local "fine tuning" of androgen biosynthesis.

Variation in the fractional conversion of plasma estrone to estriol among women and men

In the present investigation, we determined the transfer constant of conversion of plasma estrone to estriol (E3) ( [rho] E1- E3BU ) in men, postmenopausal women, and premenopausal parous and premenopausal nulliparous women. We found no significant difference in [rho] E1- E3BU among men, postmenopausal women, premenopausal parous or nulliparous women (whether the latter were studied during the midfollicular or midluteal phase of the ovarian cycle), or in women who were ingesting oral contraceptives. On the other hand, there was a striking variation in the [rho]E1- E3BU among individuals, viz. 0.02-0.27, whereas in a given individual, the variation in [rho] E1- E3BU , evaluated on separate occasions, was small. In addition, we found a negative correlation between age at first fullterm pregnancy and [rho] E1- E3BU .

Estrogen biosynthesis in human liver--a comparison of aromatase activity for C-19 steroids in fetal liver, adult liver and hepatoma tissues of human subjects

After incubation of various tritiated C-19 steroids (androstenedione, testosterone, dehydroepiandrosterone, dehydroepiandrosterone sulfate) with human fetal liver, adult liver and hepatoma tissue homogenates, estrone, estradiol and estriol were analysed after a series of purification steps involving column chromatography, thin layer chromatography and co-crystallization. The findings indicated that the human fetal liver extensively aromatized various C-19 steroids to estrogens, whereas human adult liver and hepatoma tissues exhibited little or no aromatase activities. The formation of estradiol from androstenedione in human fetal liver indicated the presence of 17 beta-hydroxysteroid dehydrogenase in this tissue. It was therefore concluded that although the liver participated in the aromatization process during the fetal stage, extensive aromatization did not take place in the adult liver.

Progesterone and estrogen production by placental monolayer cultures: effect of dehydroepiandrosterone and luteinizing hormone-releasing hormone

The effect of dehydroepiandrosterone (DHA) and LRH on estrogen and progesterone production by cultured placental cells has been investigated. Placental monolayer cultures were established by trypsin dispersion of term placental villi and were maintained for 5 days in culture medium containing either no steroid or 10(-7) - 10(-5)M DHA, DHA sulfate (DHAS), or 16 alpha-hydroxy-DHA (16 alpha-OH DHA), in all cases with and without the addition of 2 X 10(-7) or 2 X 10(-6)M LRH. The cultures were changed every 24 h, and the media collected were analyzed for estrogen and progesterone by RIA. 17 beta-Estradiol production was dependent on the presence of DHA or DHAS in the medium and increased in proportion to the concentration of precursor added. Similarly, estriol was produced in proportion to the amount of 16 alpha-OH DHA added to the medium. At the same time, high concentrations (10(-5) M) of DHA and DHAS, but not 16 alpha-OH DHA, markedly suppressed progesterone production. LRH had an inhibitory effect on both progesterone and estrogen output by the cultures. These studies suggest that not only the fetus, through its increasing adrenal production of DHA and DHAS toward term, but the placenta itself, through its production of LRH, could modulate placental steroid synthesis.

Metabolism of testosterone by GR mouse mammary tumors

The metabolism of testosterone by GR mouse mammary tumors following serial transplantation was studied. Oophorectomized female recipients were maintained on estrone and progesterone (OEP) or without hormone maintenance (oophorectomized-only group) in order to assess whether the growth of the tumor was hormone dependent (HD) or hormone independent (HI). Tumors in the early generations of the OEP group were HD (generations 1 to 4), which became HI in the latter generations (G5 to G18). All tumors developed in the oophorectomized-only group (generations 1 to 18) were HI. All tumors investigated were capable of metabolizing testosterone to 4-androstenedione, 16 alpha-hydroxytestosterone, 5 alpha-dihydrotestosterone, 5 alpha-androstanedione, and 5 alpha-androstanediol. Total 5 alpha-reduction in OEP group ranged between 50 and 60% of neutral metabolites in HD tumors and dropped to 13 to 28% in HI tumors (generations 5 to 18), similar to the activities (20 to 30%) of the HI tumors in the oophorectomized only group. Different patterns of estrogen synthesis were observed among these tumors. Although tumors showed the presence of appreciable amounts of estriol, estrone was synthesized only in 5 of the 9 HI tumors in the oophorectomized only group. The most striking contrast was that estradiol was synthesized by all HI tumors in the oophorectomized-only group and the OEP group but not in the HD tumors.

Significance of aromatase activity in human breast cancer

The significance of in vitro aromatization of [7 alpha-3H]testosterone to estradiol by human breast cancer has been investigated by correlation with (a) estrogen receptor activity and (b) clinical response to endocrine therapy. Evidence for estradiol synthesis was obtained in 66 and estrogen receptor activity in 81 of 110 tumors. Whereas most estrogen receptor-positive tumors synthesized estradiol, the majority of the receptor-negative tumors did not. This tendency for aromatization to be associated with estrogen receptor-positive tumors was statistically significant (p less than 0.005). Mean level of receptor was also significantly higher in tumors with aromatization than in tumors without estradiol synthesis (p less than 0.001). Forty patients with advanced breast cancer have been treated by endocrine therapy. There was a significant trend for tumors with aromatization to be associated with response to treatment (p less than 0.05), but the correlation was not absolute and may simply reflect the association between aromatase activity and estrogen receptors. Within the small subgroup of patients treated with aminoglutethimide or adrenalectomy, tumors with high aromatase activity responded whereas those without aromatization did not. Tumor estrogen biosynthesis may therefore be of clinical significance in selecting patients for treatments which remove sources of precursor for aromatization of inhibit aromatase activity itself.

In vitro production of estriol from four steroid precursors by rabbit tissues

The production of estriol was demonstrated in intact leukocytes and homogenates of liver, adrenals and ovaries of young adult female rabbits from 17 beta-estriol, testosterone, androst-4-ene-3,17-dione and dehydroepiandrosterone. Androst-4-ene-3,17-dione constituted the best substrate in liver and adrenals and the poorest substrate for estriol production in lymphocytes. Estriol was least readily transformed into estriol in liver and adrenals, while it proved to be the best substrate in ovaries. Phenobarbital administration to rabbits resulted in 49-fold and 23-fold increases in the transformation of androst-4-ene-3,17-dione and dehydroepiandrosterone, respectively, into estriol by lymphocytes. The results indicate that the enzymes involved in estriol biosynthesis in the various tissues respond differently to phenobarbital.

Isolated defect in human placental lactogen synthesis in a normal pregnancy. Case report

A deficiency in the synthesis of human placental lactogen (hPL) was found in a woman in her second pregnancy. Other placental hormone levels were normal. The woman gave birth to a healthy female infant. hPL deficiency is rare and a survey of the literature has revealed only one previous case report which described the birth of a male infant. The present report of a hPL deficiency is the first associated with the birth of a normal female infant.

[Endocrino-pharmacological study of reproduction: Role and biosynthesis of steroid hormones in the feto-placental unit]

Although considerable information is available concerning steroidogenesis in the human fetus, the function of the different steroids formed during pregnancy and the factors regulating this delicate hormones balance are poorly understood. During human pregnancy, the placenta synthesizes large quantities of progesterone, estradiol, estrone and estriol and secretes these hormones into both the maternal and fetal circulations; progesterone from maternal lipoprotein-cholesterol, estradiol and estrone from maternal and fetal dehydroepiandrosterone sulfate (DHAS), and estriol largely from fetal 16 alpha-OH-DHAS. It has been demonstrated that preimplantation blastocysts of several animal species have the capacity to accumulate steroids to pregnenolone to progesterone, and to interconvert estrone and estradiol. Estetrol (E4), 15 alpha-hydroxy derivative of estriol is an interesting compound, since its formation is relatively unique to fetal liver function. Of special interest is that placental sulfatase deficiencies result in an extension of the gestation, and Cesarean section has to be done. This raises the question of the role of estrogens in determining the onset of labor, much as in the case of anencephaly. In general, progesterone may decline prior to an abortion, but there has not been a direct application to clinical practice. Estrogen levels during pregnancy are influenced by factors other than fetal well-being and include fetal weight, placental enzyme function, fetal adrenal function, maternal intestinal flora, maternal renal excretion and maternal liver function. Although not yet extensively utilized, such a dynamic test as the infusion of DHAS may yield useful information within a short period in otherwise complicated cases related to fetal and placental function.

Oestrogen metabolism in adult rat's brain

In vitro incubation of pituitary, hypothalamus and cerebral cortex with [3H]oestrogens revealed that the oestrogens are actively metabolized by these tissues. The covalent binding of oestrone and oestradiol to acid precipitable proteins was observed. Pituitary from male rats exhibited higher covalent binding of oestrogens than females. The 2-hydroxylation was found to be greater than 16-hydroxylation. Furthermore, male pituitary exhibited higher 2-hydroxylation of oestrogens than females. No such sexual dimorphism was observed in 16-hydroxylation. C17-reduction was found to be greater than oxidation in these tissues. Furthermore, the C17-reduction in pituitary and hypothalamus from females was greater than males, which is in contradistinction to protein binding and 2-hydroxylation of oestrogens. In both male and female animals the pituitary was metabolically more active than hypothalamus and cortex. In addition, oestradiol was hydroxylated more than oestrone either at 2- or 16-positions. These results indicate that in central nervous system and pituitary the oestrogens are metabolized preferentially by 2-hydroxylation pathway and it is suggested that the in situ metabolism of oestrogens in neuroendocrine tissues may be important in the control of oestrogen effects on neuroendocrine function and sex behaviour.

Biosynthesis of 16 alpha, 17 alpha-epoxy-oestratrienol in rat liver microsomes

After incubation of 1,3,5(10),16-oestratetraenol, a 16-dehydrosteroid, with rat liver microsomes, 16 alpha, 17 alpha-epoxy-oestratrienol was isolated as metabolite. The compound was detected by the use of mass fragmentography after purification of the incubation extract by thin-layer chromatography. Since the epoxide is rapidly hydrolysed by a hepatic epoxide hydratase, only very small concentrations of this metabolite were present in the incubation extract. When styrene oxide was added to the incubation mixture as inhibitor of the epoxide hydratase, the yield of the steroid epoxide increased considerably. Final identification of the oestrogen epoxide was performed by recording mass spectra and by comparison with authentic reference material.

Improved synthesis of 16alpha-hydroxylated androgens: intermediates of estriol formation in pregnancy

16alpha-Hydroxyandrostenedione (16alpha-hydroxyandrost-4-ene-3,17-dione), 16alpha-hydroxytestosterone (16alpha,17beta-dihydroxyandrost-4-en-3-one) and 16alpha-hydroxydehydroepiandrosterone 3-sulfate (3beta, 16alpha-dihydroxyandrost-5-en-17-one 3-monosulfate) were synthesized by a new chemical approach with much improved yield. 16alpha-Bromoandrostendione was converted to the hydrazone of 16alpha-hydroxyandrostenedione which gave 16alpha-hydroxyandrostenedione on acid hydrolysis in total 63% yield. Oxidation of 16alpha-hydroxydehydroepiandrosterone with Jones' reagent also selectively afforded 16alpha-hydroxyandrostenedione. 16alpha-Hydroxytestosterone was observed by selective reduction of 16alpha-hydroxyandrostenedione with sodium borohydride. Reaction of 16alpha-hydroxydehydroepiandrosterone with chlorosulfonic acid in pyridine selectively gave the 3-monosulfate. The structure of the sulfate was deduced from its solvolysis to the starting material, and its acetylation and subsequent solvolysis to 16alpha-hydroxydehydroepiandrosterone 16-acetate. All procedures are suitable for large scale synthesis without the use of microorganisms.

15alpha-Hydroxyoestriol and other polar oestrogens in pregnancy monitoring

Although oestriol measurements are well established for the assessment of 'at risk' pregnancies, there are a number of other oestrogens, excreted during pregnancy, which contain additional hydroxyl groups and might be more sensitive indicators of the condition of mother or fetus. Some of these result from the action of hydroxylases possibly present only in the fetus and others from maternal hydroxylations. We review the evidence for the biosynthesis of these polar oestrogens, summarise methods of measurement, and compare values obtained in normal and pathological pregnancies. There is as yet insufficient evidence to enable their potential value to be confirmed.

A direct radioimmunoassay for estriol-16-glucuronide in urine for monitoring pregnancy and induction of ovulation

Antibodies to estriol-16alpha-[beta-D-glucuronide] were raised in sheep with the use of keyhold limpet hemocyanin and bovine serum albumin conjugates of estriol-16alpha-[beta-D-glucuronide]. A simple, rapid method is presented for direct radioimmunoassay of estriol-16alpha-[beta-D-glucuronide] in urine with dextran-coated charcoal used for separation of free from bound and deionized water used for dilutions. The method is thrifty in its use of reagents. The assay has been evaluated in the pregnancy range, and the sensitivity has been extended into the range necessary for monitoring induction of ovulation with Pergonal.

Urinary 17-ketosteroids in diabetic and non-diabetic pregnancies

The excretion of estriol into the maternal urine is an effective means of evaluating the fetus in pregnancies complicated by a number of metabolic disorders, such as chronic hypertension, renal disease, pre-eclampsia, etc. It is generally used in the management of pregnancies complicated by maternal diabetes mellitus even though some question has been raised as to its validity for this disorder. In this study we have evaluated estriol precursors in the form of 17-ketosteroids in the urine of pregnant women with mild diabetes mellitus as well as a non-diabetic control group. Urinary total estrogen excretion was also determined. Diabetics were found to excrete significantly higher amounts of 17-ketosteroids than the non-diabetic group. The possible significance of this finding in relation to the dynamics of estriol production in pregnancy is discussed.

Serum unconjugated estriol levels in the third trimester and their relationship to gestational age

Maternal unconjugated estriol levels were measured throughout the 28 to 41 week interval in two groups of accurately dated normal pregnancies. The first group consisted of randomly sampled pregnancies on which 285 unconjugated estriol determinations were performed. The logarithms of the mean values plotted into a positive sloping, relatively straight line which was disrupted by a plateau originating at 31 to 32 weeks and terminated at 35 weeks where there began a steep surge to a point at 36 weeks (surge point) that returned values to fit the previously established straight line. To investigate these findings in individual pregnancies, a second group of nine subjects was studied with serial unconjugated estriol determinations. In all nine of these subjects, the surge point could be identified statistically and occurred at a mean gestational age of 36.0 +/- 0.6 (1 S.D.) weeks. Data from the first group of randomly sampled pregnancies indicate that the surge point occurred around a mean gestational age of 36.0 weeks and was confirmed by data from the second group of serially sampled individual subjects showing the surge point as a statistically definable marker in normal pregnancies.

[The thioacetamide-poisoned rat as an animal experimental model for endocrinological studies of estrogen metabolism in chronic liver injury)]

Liver microsomes of rats poisoned with thioacetamide show a significant reduction of cytochrome P-450. Consequently, oxidative reactions of drug metabolism and the estrogen 2-hydroxylase are diminished. Enhancement of microsomal transformation of estradiol to estrone and 16alpha-hydroxyestrone is observed after treatment of rats with thioacetamide, due to diminished metabolism of estradiol by the alternative oxidation at C-2. Estriol formation is reduced by thioacetamide pretreatment. These changes in estrogen breakdown closely correlate with those observed in humans suffering from cirrhosis of the liver. It is concluded that the thioacetamide poisoned rat should be an experimental model suitable for studying estrogen metabolism in liver injury.