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At least 19 recordsLinked to original sources
PubMed1975

(3H)-estradiol binding by chick liver nuclear extracts: mechanism of increase in binding following estradiol injection.

Specific high affinity binding of [3H]-estradiol by 0.5 M KCl extracts of chick liver nuclei is substantially increased by estradiol injection of the immature chick. The effect is observed shortly after estradiol injection, while the estradiol-induced production of serum phosphoproteins (vitellogenic response) is not detectable until about 24 hr. Cycloheximide given 90 min before estradiol inhibits the increase in nuclear binding for 12-15 hr. At 24-48 hr the levels of nuclear binding are similar to those in the estradiol-treated animals not given cycloheximide, but serum phosphoprotein levels are depressed by about 80% at 48 hr. By 75 hr however the serum of the cycloheximide-treated estrogenized chicks contains about twice as much phosphoprotein as does serum of chicks given estradiol alone. It is suggested that the inhibition of protein synthesis for 12-15 hr delays the vitellogenic response until sufficient levels of nuclear [3H]-estradiol binding protein can be synthesized. A correlation between the levels of nuclear [3H]-estradiol binding at 24 hr and phosphoprotein at 48 hr is shown in a dose-response experiment. In vitro, nafoxidine-HCl (Upjohn 11,100 A) inhibits binding of [3H]-estradiol by the chick liver nuclear extracts. In vivo, a single injection of nafoxidine with estradiol inhibits phosphoprotein production. Injection of nafoxidine alone results in a small but significant increase in [3H]-estradiol binding by nuclear extracts, but it is not estrogenic. A possible interpretation is that nafoxidine transfers low levels of a putative cytosol receptor to the nucleus, but is unable to induce the amplification mechanism required to give the levels of nuclear estradiol-binding protein needed for the vitellogenic response.

Animals↗
PubMed1976

Limited proteolysis of cytoplasmic and nuclear uterine estradiol receptors yields identical estradiol-binding fragments.

Limited tryptic hydrolysis of the estradiol cytoplasmic receptor from calf uterus has been demonstrated to yield in a high-salt buffer a stable estradiol-binding molecule with the following characteristics: sedimentation coefficient 4.0 +/- 0.1 S; Stokes radius 3.5 +/- 0.05 nm; molecular weight 60000 (for an assumed v value of 0.73 ml g-1) and frictional ratio 1.36. Nuclear KCl extracts, prepared from uteri preincubated at 37 degrees C with labeled estradiol, were analysed by Sephadex G-200 chromatography and sucrose density gradient centrifugation. The following molecular parameters were found for the estradiol-receptor complex: sedimentation coefficient 4.4 +/- 0.1 S; Stokes radius 4.12 +/- 0.02 nm; molecular weight 77000 and frictional ratio 1.47 (v = 0.73 ml g-1). Limited tryptic proteolysis of this extract gave an estradiol-binding fragment with molecular characteristics identical to the trypsin-modified cytoplasmic receptor. In addition, mild tryptic digestion of whole labeled nuclei allowed us to solubilize almost quantitatively the nuclear [3H]estradiol in a macromolecular bound form. The molecule thus obtained showed molecular parameters very similar to the 60000-dalton trypsin fragments obtained from high-salt cytoplasmic and nuclear extracts. These molecules were undistinguishable by gel electrophoresis analysis at six different acrylamide concentrations. These results in conjunction with those derived from dissociation kinetics experiments and ligand specificity studies indicate the cytosolic protein is a functional part of the nuclear receptor. Based upon these and other studies we suggest that proteolytic cleavage of the estradiol-receptor complex, which results in the removal of the estradiol-binding sites from the nuclear recognition sites of the molecule, could play a role in the inactivation of the estradiol receptor in vivo.

Animals↗
PubMed1975

Estradiol receptor content in rat granulosa cells during follicular development: modification by estradiol and gonadotropins.

To examine the relationships between gonadotropic hormones, ovarian follicular development, and estradiol receptor content in rat granulosa cells, follicular growth was stimulated in intact immature rats and hypophysectomized immature rats. In intact rats, both PMSG and oFSH given for 2 days stimulated follicular growth and endogenous estrogen production but caused estradiol receptor content in granulosa cells to decrease markedly. In hypophysectomized rats estradiol (2 mg/day X 4) was capable of increasing the content of its own receptor, stimulated preantral follicular development, and potentiated the responses of granulosa cells to highly purified hFSH. Thus, subsequent treatment with hFSH stimulated antral formation and maintained high levels of estradiol receptor content in granulosa cells. LH, on the other hand, caused a rapid decline in the content of estradiol receptor in nuclei of granulosa cells. In hypophysectomized rats primed with estradiol alone, a high dose of oLH caused follicles to undergo atresia. In hypophysectomized rats primed with hFSH in addition to estradiol, oLH stimulated luteinization. Thus, induction of atresia or luteinization by oLH in these rats appears to be associated (cause or effect?) with a loss of estradiol receptor in granulosa cells. Whether follicles of estrogen-treated, hypophysectomized rats luteinize or undergo atresia in response to LH appears to be determined by their stage of differentiation and the nature of the prior stimulation by FSH.

Aging↗
PubMed1979

Serum levels of estrone and estradiol after implantation of estradiol pellets.

Serum estrone, estradiol, progesterone, FSH, and LH levels were studied after the implantation of estradiol pellets in female volunteers in the reproductive age group. The estradiol pellets were implanted at six-month intervals. The first implant consisted of four pellets (25 mg each). Subsequent implants consisted of a reduction by one pellet as compared to the previous implant. The mean serum estradiol levels during the six-month period of implantation or at the end of six-month intervals were in the premenopausal range and did not differ significantly during the study. The serum estrone levels showed a tendency to increase with time even though the number of pellets implanted was decreasing, apparently a result of incomplete absorption of the implanted estradiol during the six-month period. The results of serum progesterone determinations and basal body temperature records indicate that the suppression of ovulation takes place most consistently during the second and subsequent months after estradiol pellet implantation.

Adolescent↗
PubMed1979

Ovulation inhibition with a combined oral contraceptive containing 20 micrograms ethinyl estradiol and 250 micrograms levonorgestrel. Serum levels of the active ingredients and FSH, LH, estradiol 17-beta and progesterone.

In order to investigate the possible ovulation inhibitory effect of a new oral contraceptive containing a combination of 20 micrograms ethinyl estradiol and 250 micrograms levonorgestrel peripheral serum from five healthy women between 17 and 24 years were analysed for FSH, LH, estradiol 17-beta and progesterone. The measurements were carried out during a control cycle before the treatment, during two treatment cycles and during a subsequent control cycle. In addition, serum levels of ethinyl estradiol and norgestrel were determined during the treatment periods. Radioimmunological methods were utilized for all the measurements. In all five women studied there was a complete inhibition of ovulation during treatment as indicated by a lack of mid-cycle LH peaks and by suppression of normal luteal phase levels of progesterone. Four out of the five women showed no biphasic estradiol pattern. During treatment the serum levels of levonorgestrel varied between 1 and 10 nmol/l while the levels of ethinyl estradiol usually were below the limit of detection for the method used (below 85 pmol/l). Post-treatment control cycles revealed a re-establishment of the ovulatory pattern in four of the five subjects.

Adolescent↗
PubMed1976

[Liver function tests under the influence of sequential treatment using ethinyl estradiol-norethisterone acetate and ethinyl estradiol-chlormadinone acetate].

30 young healthy women were investigated during the first therapy cycle with ethinyl-estradiol-norethisterone acetate and ethinyl-estradiol-chlormadinone acetate as a sequential regime. The following laboratory data were achieved by each of the investigated group of young women: serum aminotransferase (GOT and GPT), serum alkaline phosphatase and alpha-amylase-activity in serum, serum proteins, serum cholesterol, serum bilirubin, serum ZST, serum TTT and the indocyaningreen-clearance of the liver. The serum protein pattern was determined by the paper electrophoretic method. A significant decrease of the aminotransferase GPT was viable during the sequential therapy with ethinyl-estradiol and norethisterone acetate. This viable decrease of the GPT was induced through the application of norethisterone acetate to estrogen. The alkaline phosphatase was significant lightly lower and the beta-globuline lightly elevated at the end of the therapy cycle. The sequential therapy with ethinyl-estradiol and chlormadinone acetate induced only a significant increase of the ZST in serum.

Adolescent↗
PubMed1977

Direction of estradiol metabolism as a control of its hormonal action--uterotrophic activity of estradiol metabolites.

The uterotrophic activities of the catechol metabolites of estradiol 2-hydroxyestrone, 2-methoxyestrone and 2-hydroxyestradiol were measured under conditions of continuous administration of sc implanted paraffin pellets. The activity of these estrogens was compared to that of estradiol-17beta and its other principal metabolites estrone, estriol and 15alpha-hydroxyestriol (estetrol). The major catechol estrogens, 2-hydroxyestrone and 2-methoxyestrone, and the pregnancy metabolite, 15alpha-hydroxyestriol, exhibited no uterotrophic activity. The minor catecholestrogen, 2-hydroxyestradiol, showed some activity whose character was different from that exhibited by implants of estradiol, estrone and estriol all of which were equipotent uterotrophic agents. Implants of 2-hydroxyestrone in the presence of estradiol or estriol pellets did not diminish the response to the latter indicating that the 2-hydroxyestrone is not antiestrogenic under these conditions. It is concluded that the direction of estradiol metabolism can have a profound influence on the expression of peripheral hormonal activity with hydroxylation at C-2 terminating and hydroxylation at C-16 extending it.

Animals↗
PubMed1975

Catalytic competence, a new criterion for affinity labeling. Demonstration of the reversible enzymatic interconversion of estrone and estradiol-17 beta covalently bound to human placental estradiol-17 beta dehydrogenase.

Human placental estradiol-17beta dehydrogenase is rapidly inactivated upon treatment with 3-bromoacetoxyestrone. Pseudo-first order kinetic data are obtained and inactivation is accompanied by incorporation of 1 mol of 3-acetoxyestrone/mol of subunit (Mr =34,000). Treatment of the inactivated enzyme with (4S)-[4-2H]DPNH results in the formation of covalently bound [17alpha-2H]estradiol-17beta, which can be released by hydrolysis and identified by gas chromatography-mass sepctrometry. When (4R)-[4-2H]DPNH was used, deuterium was not transferred. Thus, the normal stereochemistry of hydridetransfer is preserved for both partners. After treatment with p-mercuribenzoate, affinity-labeled estradiol-17beta dehyrogenase is no longer able to caralyze reduction its covalently bound estrone; in the presence of DPNH and native enzyme, however, reduction occurs, demonstrating that affinity-labeled enzyme can itself serve as subtrate for native estradiol-17beta dehydrogenase. The reversible enzymatic interconversion of covalently bound estrone was demonstrated using a transhydrogenase assay. The ability of an enzyme to catalyze its normal reaction with a covalently bound substrate is termed catalytic competence, and is considered to be a new criterion for affinity labeling.

Affinity Labels↗
PubMed1979

Estradiol 17 beta-dehydrogenase and estradiol binding in human mammary tumors.

The metabolism of estradiol was studied in 31 human breast carcinoma in vitro. All 16 estrogen-receptor-poor tumors transformed estradiol to estrone with percent conversions ranging from 11.4 to 95 except for one poorly differentiated tumor where 0.5% conversion to estrone was observed. On the contrary, only 3 out of 15 estrogen-receptor-rich tumors showed higher than 10% conversion of estradiol to estrone (p = 0.001). There is indication that the enzymatic activity in receptor-poor tumors steadily decreases in premenopausal patients as they approach menopausal age, whereas, the activity steadily increases in post-menopausal patients as the duration of menopause lengthens.

17-Hydroxysteroid Dehydrogenases↗
PubMed1979

An assay for estradiol preceptors using a staphylococcal protein-A--estradiol antibody adsorbent.

Antiestradiol antisera were raised in rabbits by immunization with a steroid-protein conjugate Whole antisera and purified antiestradiol antibodies were reacted with heat-killed and formalin-fixed bacteria from the protein-A-bearing strain of Staphilococcus aureus (Cowan I, NCTC 8530). The bacterial immunoadsorbent was used to estimate the estrogen-receptor proteins contained in several specimens from human breast carcinoma. Since the affinity constant for estradiol of antiestradiol antibodies is about 10(8) M-1 while those for breast estrogen-receptor complexes are about 10(9) to 10(10) M-1, it is possible to remove the free steroid from a reaction mixture containing tissue cytosol, radio-labelled estradiol, and the antiestradiol bacterial adsorbent by pelleting the bacteria at low-speed centrifugation. The radiolabelled estradiol molecules bound to their receptors remain in the supernatant and can be easily counted by liquid scintillation counting. The results obtained by this technique on specimens of human breast carcinomas compared more than satisfactorily with those obtained, on separated aliquots from the same specmens, by the dextran-coated charcoal method, according to the EORTC group (1973). The versatility, specificity and stability of the antiestradiol bacterial immunoadsorbent recommend its use, rather than that of charcoal-coated dextran and other non-specific steroid adsorbents, in the mass screening of patients with breast carcinoma which could be amenable to hormonal therapy.

Animals↗
PubMedDate not supplied

Testosterone-estradiol-binding globulin, unbound and total estradiol and testosterone, and total progesterone during the menstrual cycle in women with epilepsy taking antiepileptic drugs.

Total plasma estradiol, progesterone, testosterone, and the binding capacity of testosterone-estradiol-binding globulin (TeBG) were measured and plasma unbound estradiol and testosterone calculated, every second day during nine cycles in six patients with epilepsy. They all received phenytoin as one medication. Some had additionally, phenobarbital or ethosuximide. Plasma concentrations were compared with those of a group of healthy women without medication. Total plasma testosterone and TeBG binding capacity were significantly increased in the treated group, as compared to the control group. However, the unbound testosterone concentration was within the range of the controls. The percentage unbound testosterone of total plasma concentration was clearly below that of the control group. This indicates that there was a primarily increased TeBG binding capacity in patients taking antiepileptic drugs.

Adolescent↗
PubMed1979

Studies on the mechanism of estradiol uptake by rat uterine cells and on estradiol binding to uterine plasma membranes.

A method for the preparation of viable uterine cell suspensions is described. Using this system the kinetics of estradiol uptake were studied in order to asses whether the steroid enters uterine cells by passive diffusion (1) or protein mediated diffusion (2). The data presented show that a) the rates of estradiol entry are nonsaturable; b) temperature dependence of uptake kinetics gives a linear Arrhenius plot; c) E2-6-CMO-BSA does not inhibit 3H-E2 uptake; d) uterine plasma membranes do not contain specific estrogen binding sites. Thus, estrogen uptake occures by passive diffusion.

Animals↗
PubMed1977

A study of prostaglandin F2alpha as the luteolysin in swine: III effects of estradiol valerate on prostaglandin F, progestins, estrone and estradiol concentrations in the utero-ovarian vein of nonpregnant gilts.

Polyvinyl catheters were placed into the right and left utero-ovarian veins and saphenous vein and artery of three control (C) and four estradiol valerate (EV) treated gilts on Day 9 after onset of estrus. The EV treated gilts received 5mg EV/day on Days 11 through 15 after onset of estrus. On Days 12 through 17 utero-ovarian vein blood samples were collected at 15 min intervals from 0700 to 1000 hr and 1900 to 2200 hr and single samples were taken at 1100 and 2300 hr. Peripheral blood samples (saphenous vein or artery) were taken at 0700, 1100, 1900 and 2300 hr from Day 12 until the control gilts returned to estrus or until Day 25 for EV treated gilts and used to measure plasma steroid hormone concentrations. Utero-ovarian vein prostaglandin F (gf) concentrations (ng/ml, n-1,177) were measured by RIA. Status (control vs EV treated gilts) by day interactions were detected (P=.10). Curvilinear day trends were detected for plasma PGF concentrations in control (P less than .01) but not EV treated gilts. PGF concentrations (X +/- S.D.) for control and EV treated gilts were 1.20 +/- 2.08 and .26 +/- .84 ng/ml, respectively. PGF peaks (concentrations greater than X + 2 S.D.) occurred with greater frequency in control gilts (X2 =4.87; P less than .05). The interestrus interval (X +/- S.E.) for control and treated gilts was 19.0 +/- .6 and 146.5 +/- 74.8 days, respectively. Data indicate tht t estradiol valerate may exert its luteotrophic effect by preventing PGF release from the uterus.

Animals↗
PubMed1975

Identification of radioactive 17beta-estradiol-17-beta-D-glucuronide and 17alpha-estradiol-17-beta-D-glucuronide in the urine of the domestic fowl after intramuscular injection of [4-14C]estrone.

Two previously uncharacterized radioactive estrogen conjugates, 17beta-estradiol-17-beta-D-glucuronide (3-hydroxyestra-1,3,5(10)-trien-17beta-D-glucopyranosiduronate) and 17alpha-estradiol-17beta-D-glucuronide (3-hydroxyestra-1,3,5(10)-trien-17alpha-yl-beta-D-glucopyranosiduronate), have been identified in small but significant amounts in avian urine and in a ratio of approximately 2:1 after intramuscular injection of [4-14C]estrone.

Animals↗
PubMed1979

Relative binding of testosterone and estradiol to testosterone-estradiol-binding globulin.

The binding of estradiol (E2) and testosterone (T) to testosterone-estradiol-binding globulin (TeBG) was studied in vivo at 37 C by three independent methods: equilibrium dialysis, steady state polyacrylamide gel electrophoresis, and TeBG-ligand dissociation kinetics. Equilibrium dialysis was performed at 37 C with the dialysate containing human serum albumin in amounts equivalent to that of the plasma dialysand. Scatchard analysis indicated that under these conditions E2 does not measurably bind to TeBG, while T has a Kd of 3.7 X 10(-10) M. Similarly, Scatchard-type analysis of E2 binding to TeBG in steady state polyacryalmide gel electrophoresis at 37 C revealed no high affinity saturable binding, while dihydrotestosterone was bound with a Kd of 2.7 X 10(-10) M. Examination of the dissociation kinetics of T and E2 ffrom TeBG revealed that the mean (+/-SD) T1/2 of dissociation of T from plasma at 37 C (10.8 +/- 2.4 min) was significantly shortened to 3.5 +/- 0.4 min by saturation of plasma with dihydrotestosterone (P less than 0.01), whereas that of E2 (8.9 +/- 1.4 min) was not changed (9.6 +/- 3.0 min). These data suggest that TeBG is not an important binder of plasma E2 at physiological temperatures and explain the observation that in diseases characterized by high TeBG levels, such as hyperthyroidism and liver disease, the MCR and free E2 levels have generally been normal.

Adult↗
PubMed1979

Estrogen receptor assay of mammary carcinomas. Effects of testosterone-estradiol-binding globulin (TeBG) and serum estradiol-17 beta.

To test the hypothesis that the serum sex steroid-binding protein, TeBG, might contaminate mammary carcinoma cytosols sufficiently to interfere with assay for estrogen receptor (ER), studies of tritiated estradiol-17 beta (3H-E2) binding were done following saturation with steroid hormones or after heat treatment of cytosol. Cytosols with appreciable 3H-E2 binding consistently showed a high degree of saturability with nonradioactive E2 and diethylstilbestrol (DES), and much less saturability with 5 alpha-dihydrotestosterone (DHT). Furthermore, they manifested heat-lability of 3H-E2 binding. These characteristics indicated that little, if any, TeBG was being detected in most cytosols, and that the amounts of TeBG present were not sufficient to interfere with the ER assay. Study of the relationship between serum E2 concentration at time of removal of the carcinoma and results of ER assay confirmed the need to interpret negative ER assays obtained for premenopausal women cautiously when serum E2 levels exceed approximately 300 pg/ml.

Adult↗