APMIS. 2001 Jan;109(1):32-8.
Assessment of estradiol and its metabolites in meat.

Maume D, Deceuninck Y, Pouponneau K, Paris A, Le Bizec B, Andre F.

LDH/LNR--Ecole Nationale Veterinaire de Nantes, Route de Gachet, Nantes, France.

Most studies related to research on steroids in main edible tissues (muscle, liver or kidney) have focused on measurement of parent or major metabolite residues. In order to evaluate the estradiol content in bovine edible tissues, a multi-step extraction procedure was developed in conjunction with parallel metabolism studies of [14C]-17beta-estradiol in cattle (1-2). Various classes of free estradiol and conjugates were separated: estradiol -17beta and -17alpha, estradiol-17-fatty acid esters, estradiol 17-glycoside, estradiol 3-glucuronide, estradiol-17-glycoside and 3- glucuronide (diconjugates) were separated. No sulphates conjugated forms have been found at the detection level of the method. The quantification was realized by calibration with deuterated 17beta -estradiol -d3 standard and was validated at the ng x kg(-1) (ppt) level. Muscle, liver, kidney and fat samples from control or Revalor S single (licensed implantation) or multi-implanted steers have been assayed. The results show a wide variation between animals, but both the highest value and the mean of total estradiol content in each group proportionally increase from untreated to multi-implanted animals. In accordance with international rules, a calculation of the daily food supply of estradiol by such edible tissues in comparison with the acceptable daily intake was performed.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11297192&dopt=Abstract estradiol




Domest Anim Endocrinol. 2003 Jan;24(1):43-57.
Steroid hormone concentration profiles in healthy intact and neutered dogs before and after cosyntropin administration.

Frank LA, Rohrbach BW, Bailey EM, West JR, Oliver JW.

Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37996-4544, USA. lfrantk.edu

The purpose of this study was to determine steroid hormone concentration profiles in healthy intact and neutered male and female dogs. Seventeen intact female dogs, 20 intact male dogs, 30 spayed female dogs, and 30 castrated male dogs were used in this study. Serum samples were collected before and 1h after cosyntropin administration, and serum concentrations were determined for cortisol, progesterone, 17-OH progesterone (17-OHP), dehydroepiandrosterone sulfate (DHEAS), androstenedione, testosterone, and estradiol. Intact male dogs had greater concentrations of DHEAS, androstenedione, and testosterone. Intact female dogs had greater concentrations of progesterone. There was no significant difference in estradiol concentration among the four groups. Intact male dogs had lower concentrations of cortisol post-stimulation. DHEAS and testosterone did not increase in response to ACTH in intact males, and estradiol concentrations did not increase in response to ACTH in any group. Results from this study will enhance interpretation of suspected adrenal and/or gonadal disorders of dogs. Because estradiol concentrations were similar in all groups of dogs, measuring estradiol may not be a useful diagnostic test. Cortisol concentrations for intact male dogs with hyperadrenocorticism may be lower than those of female or neutered dogs. Copyright 2002 Elsevier Science Inc.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12450624&dopt=Abstract estradiol




Transplantation. 2002 Nov 15;74(9):1252-9.
17beta-Estradiol protects isolated human pancreatic islets against proinflammatory cytokine-induced cell death: molecular mechanisms and islet functionality.

Contreras JL, Smyth CA, Bilbao G, Young CJ, Thompson JA, Eckhoff DE.

Transplant Center, University of Alabama at Birmingham, Birmingham, AL, USA. Juan.Contreracc.uab.edu.

INTRODUCTION: Proinflammatory cytokines (PIC) (interleukin-1beta, interferon-gamma, and tumor necrosis factor alpha) are released after intraportal islet transplantation lead to functional suppression and islet apoptosis. Estradiol has been shown to promote survival of cells undergoing PIC-induced apoptosis. In this study, we evaluated the effects of estradiol on isolated human pancreatic islet (IHPI) survival after exposure to PIC and analyzed potential mechanisms of action. METHODS: Hand-picked, freshly isolated IHPI were incubated with PIC and estradiol. Viability was analyzed from single islet cells stained with ethidium bromide and acridine orange, apoptosis using a quantitative kit, NF-kappaB nuclear translocation using a promoter-Luciferase NF-kappaB responsive construct, mitochondrial permeability transition using the ApoAlert Mitochondrial kit, and caspase 9 by a fluorometric assay. In vitro functionality was examined by static incubation, and a limited number of islets were transplanted in nonobese diabetic, severe combined immunodeficient mice. RESULTS: 17beta-Estradiol induced a dose-dependent increase in islet viability, an effect partially reversed by the estrogen receptor antagonist ICI 182,780. In vitro, islets treated with estradiol presented higher stimulation index. Euglycemia was achieved in 6 of 12 animals that received estradiol-treated islets compared with 1 of 12 control animals. Lower NF-kappaB nuclear translocation, cytochrome release, and caspase 9 activation occurred in islets treated with estradiol. CONCLUSIONS: Estradiol promoted IHPI survival and improved functionality after PIC exposure in vitr




J Neurosci. 2001 Apr 15;21(8):2600-9.
Differential mechanisms of neuroprotection by 17 beta-estradiol in apoptotic versus necrotic neurodegeneration.

Harms C, Lautenschlager M, Bergk A, Katchanov J, Freyer D, Kapinya K, Herwig U, Megow D, Dirnagl U, Weber JR, Hortnagl H.

Institute of Pharmacology and Toxicology and Department of Neurology, Medical Faculty Charite, Humboldt-University at Berlin, D-10098 Berlin, Germany.

The major goal of this study was to compare mechanisms of the neuroprotective potential of 17 beta-estradiol in two models for oxidative stress-independent apoptotic neuronal cell death with that in necrotic neuronal cell death in primary neuronal cultures derived from rat hippocampus, septum, or cortex. Neuronal apoptosis was induced either by staurosporine or ethylcholine aziridinium (AF64A), as models for necrotic cell death glutamate exposure or oxygen-glucose deprivation (OGD) were applied. Long-term (20 hr) pretreatment (0.1 microm 17 beta-estradiol) was neuroprotective in apoptotic neuronal cell death induced by AF64A (40 microm) only in hippocampal and septal neuronal cultures and not in cortical cultures. The neuroprotective effect was blocked by the estrogen antagonists ICI 182,780 and tamoxifen and the phosphatidylinositol 3-kinase (PI3-K) inhibitor LY294002. In glutamate and OGD-induced neuronal damage, long-term pretreatment was not effective. In contrast, short-term (1 hr) pretreatment with 17 beta-estradiol in the dose range of 0.5-1.0 microm significantly reduced the release of lactate dehydrogenase and improved morphology of cortical cultures exposed to glutamate or OGD but was not effective in the AF64A model. Staurosporine-induced apoptosis was not prevented by either long- or short-term pretreatment. The strong expression of the estrogen receptor-alpha and the modulation of Bcl proteins by 17 beta-estradiol in hippocampal and septal but not in cortical cultures indicates that the prevention of apoptotic, but not of necrotic, neuronal cell death by 17 bet




Neuroendocrinology. 2001 Mar;73(3):166-74.
Estrogens act in rat hippocampus and frontal cortex to produce rapid, receptor-mediated decreases in serotonin 5-HT(1A) receptor function.

Mize AL, Poisner AM, Alper RH.

Department of Pharmacology, Toxicology and Therapeutics, The University of Kansas School of Medicine, 3901 Rainbow Blvd., Kansas City, KS 66160-7417, USA.

Previously our laboratory has shown that 17beta-estradiol in vivo rapidly decreases R(+)-8-OH-DPAT-stimulated [(35)S]GTPgammaS binding (a measure of the initial biochemical event in the intracellular signaling pathway associated with 5-HT(1A) receptors) in the hippocampus, frontal cortex and amygdala. Studies were designed to determine if 17beta-estradiol also acts in vitro on estrogen receptors in the hippocampus and frontal cortex to decrease 5-HT(1A) receptor function. Hippocampus and frontal cortex were dissected from ovariectomized rats and incubated for up to 3 h with various estrogens and antiestrogens; membrane homogenates were prepared for R(+)-8-OH-DPAT-stimulated [(35)S]GTPgammaS binding assays. 17beta-Estradiol (10(-6) M) decreased the maximal response in the R(+)-8-OH-DPAT-stimulated [(35)S]GTPgammaS binding assay in a time-dependent manner (observed at 30, 60 and 120 min) in both hippocampus and frontal cortex. The hormone, however, did not alter the EC(50) of R(+)-8-OH-DPAT. When hippocampus and frontal cortex were incubated in graded concentrations of 17beta-estradiol for 1 h, the calculated EC(50) was approximately 2.5 x 10(-8) M in both brain regions. The nonestradiol estrogen diethylstilbestrol also decreased 5-HT(1A) receptor function while the less potent estrogens 17alpha-estradiol and estriol were inactive at 5 x 10(-8) M. The estrogen receptor antagonist ICI 182,780 potently and completely blocked the effects of 17beta-estradiol on 5-HT(1A) receptor function with an apparent K(B) of approximately 10(-9) M. These data demonstrate clearly that estrogens can act on estrogen receptors located in hippocampus and f




Eur J Obstet Gynecol Reprod Biol. 2001 May;96(1):98-101.
Luteal phase hormonal profile in prediction of pregnancy outcome after assisted reproduction.

Vicdan K, Zeki Isik A.

Assisted Reproductive Technologies Center, Bayindir Hospital, Menevis Sokak 30/6, 06540 A. Ayranci, Ankara, Turkey. kvicdaurf.net.tr

The clinical efficacy of luteal phase hormones including estradiol and progesterone in the prediction of pregnancy and its outcome in ICSI-ET cycles was evaluated. In 121 ICSI-ET cycles, serial estradiol and progesterone levels were measured in the luteal phase. The day of ovum pick-up was designated as day 0. All the patients had luteal support with vaginal progesterone suppositories after embryo transfer (ET). Serial estradiol measurements were performed on days 8, 11 and 13 and progesterone level on day 11. A single dose of hCG was given for corpus luteum rescue 5000 IU, if day 8 estradiol level <200pg/ml; 2000IU, if estradiol between 200 and 800pg/ml; no hCG if estradiol level >800pg/ml). On day 15, beta-hCG level was measured to detect pregnancy and if positive, injected on day 17. Fifty-seven pregnancies were achieved in 121 cases after ET (47%). Clinical pregnancy rate and ongoing pregnancy rate per ET were 37.1 and 30%, respectively. While there was no difference between progesterone levels measured on day 11, estradiol levels on days 11 and 13 were significantly higher in women who became pregnant. In 40 patients taking only progesterone and in 81 cases taking hCG plus progesterone, estradiol levels on days 11 and 13 were significantly higher in women who became pregnant. Progesterone levels on day 11, in progesterone treated groups, did not differ between pregnant and non-pregnant patients. Estradiol and progesterone levels on day 11 and estradiol levels on day 13 showed a big overlap between pregnant and non-pregnant patients. The efficacy of serial testing was evaluated. An increase in estradiol level from day 11 to 13 was associated with 71% pregnancy rate (72% ongoing). In the case o




Toxicol Appl Pharmacol. 2001 May 1;172(3):217-24.
Mono-(2-ethylhexyl) phthalate suppresses aromatase transcript levels and estradiol production in cultured rat granulosa cells.

Lovekamp TN, Davis BJ.

Department of Environmental and Molecular Toxicology, North Carolina State University, Raleigh, North Carolina, 27695, USA.

The female reproductive toxicity of di-(2-ethylhexyl) phthalate and its active metabolite mono-(2-ethylhexyl) phthalate (MEHP) is attributed to suppression of ovarian granulosa cell estradiol production. In these studies, several structurally related phthalates (0-200 microM) and Wy-14,643 (0-100 microM) were compared to MEHP for their effects on granulosa cell estradiol production and transcript levels of cytochrome P450 enzyme CYP 19, also known as aromatase (P450arom), the rate-limiting enzyme in the conversion of androgens to estrogens. Granulosa cells were obtained from 28-day-old Fisher 344 rats and were cultured for 48 h. Test chemical or DMSO was added at the time of culture, along with testosterone as a substrate for aromatase. 17beta-Estradiol production was measured by standard radioimmunoassay, mRNA was measured by fluorescent RT-PCR, and protein was measured by Western blot analysis. MEHP was unique among the phthalates in its ability to decrease estradiol production, while Wy-14,643 had effects similar to MEHP at 100 microM. MEHP and Wy-14,643 also significantly decreased aromatase mRNA levels. The decrease in mRNA was concentration dependent and was paralleled by a decrease in aromatase protein. MEHP did not alter levels of CYP 11A1, the cholesterol side-chain cleavage enzyme (P450scc). Treatment with a cAMP analogue increased expression of P450scc in the presence of MEHP (100 to 200 microM) while the decrease in aromatase remained. Thus, these studies suggest that MEHP is distinct from several structurally related phthalates but similar to the peroxisome proliferator Wy-14,643 in its action on granulosa cell estradiol production. Moreover, the suppression of estradio




Biol Reprod. 2001 May;64(5):1526-34.
Modulation of potassium current characteristics in human myometrial smooth muscle by 17beta-estradiol and progesterone.

Knock GA, Tribe RM, Hassoni AA, Aaronson PI.

The London Myometrium Group, Centre for Cardiovasular Biology and Medicine, New Hunt's House, Guy's Campus, London SE1 1UL, United Kingdom. greg.knoccl.ac.uk

The K(+) channel currents are important modulators of smooth muscle membrane potential and excitability. We assessed whether voltage-gated K(+) currents from human myometrium are regulated by placental steroid hormones during pregnancy and labor. Pregnant human myometrial cells were isolated from samples obtained at cesarean section. Primary cultured cells were treated with 100 nM 17beta-estradiol, 1 microM progesterone, or both hormones in combination for 24 h. Acute effects of the two hormones were also determined. The K(+) currents were recorded using the standard whole-cell, patch-clamp technique. Primary cultures possessed both delayed rectifier (I(KV)) and A-like (I(KA)) voltage-gated K(+) currents. The 24-h 17beta-estradiol treatment caused a hyperpolarizing shift in the steady-state inactivation of both I(KV) and I(KA). Progesterone treatment also shifted the inactivation of I(KA) and increased I(KV) amplitude by 60%-110%. Conversely, the combined treatment had no effect on these currents. Neither 17beta-estradiol (0.1-1 microM) nor progesterone (1-5 microM) had any effect on the K(+) current when applied acutely. These results show that 17beta-estradiol should inhibit myometrial K(+) channel activity, whereas progesterone is likely to have the opposite effect. These results are consistent with the respective procontractile and proquiescence roles for 17beta-estradiol and progesterone in human uterus during pregnancy.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11319161&dopt=Abstract estradiol




Mutagenesis. 2001 May;16(3):209-12.
Increased formation of micronuclei after hormonal stimulation of cell proliferation in human breast cancer cells.

Fischer WH, Keiwan A, Schmitt E, Stopper H.

Department of Toxicology, University of Wurzburg, Versbacher Strasse 9, D-97078 Wurzburg, Germany.

The carcinogenicity of sex hormones is considered to be the result of a combination of genotoxic and epigenetic modes of action. For estrogens, genotoxic activities include DNA damage by reactive metabolites and indirect genotoxicity by redox cycling and production of reactive oxygen species. Here, we present data on the induction of micronuclei in estrogen receptor-positive (MCF-7) and -negative (MDA) human breast cancer cell lines treated with estradiol to support an additional mechanism of chromosomal damage. MCF-7 cells, but not MDA cells, treated with estradiol in the picomolar concentration range showed an increase in micronucleus formation which correlated with the estradiol-induced cell proliferation. Addition of the specific estradiol-receptor antagonist hydroxytamoxifen suppressed the estradiol-induced formation of micronuclei in MCF-7 cells. Increased frequencies were also seen after normalization of the data to the number of cell divisions by additional treatment of the cells with cytochalasin B. Thus, formation of micronuclei was not due to the chromosomal damaging activity of estradiol. The induced genomic damage may be explained by a hormone-specific forcing of responsive cells through the cell cycle, thereby overriding checkpoints operating under homeostatic control of the cell cycle.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11320145&dopt=Abstract estradiol