Hypertension. 2004 Jul;44(1):78-82. Epub 2004 May 24.
Estrogen and tamoxifen modulate cerebrovascular tone in ovariectomized female rats.

Tsang SY, Yao X, Chan FL, Wong CM, Chen ZY, Laher I, Huang Y.

Department of Physiology, Chinese University of Hong Kong, Shatin, Hong Kong.

Postmenopausal estrogen deficiency increases the incidence of cerebrovascular disease. However, hormone replacement therapy is associated with an increased cardiovascular risk. Tamoxifen is a selective estrogen receptor modulator with estrogenic effects on cardiovascular risk factors, but its long-term impacts on cerebral vasculature are unknown. We hypothesized that chronic 17beta-estradiol or tamoxifen treatment exerted similar effects in reducing cerebrovascular tension in ovariectomized rats. We therefore determine whether (1) chronic 17beta-estradiol treatment could influence vasomotor activities, (2) chronic tamoxifen therapy could exert an estrogen-like or estrogen-antagonistic effect, and (3) acute exposure to estrogen could mimic the effect of 17beta-estradiol. Isometric tension was measured in cerebral arteries from female rat groups: control, ovariectomy, ovariectomy plus 17beta-estradiol treatment, ovariectomy plus tamoxifen treatment, and ovariectomized rats treated with tamoxifen and 17beta-estradiol. Ovariectomy enhanced cerebrovascular contractions to endothelin-1 or CaCl2, but not to U46619 or phenylephrine. 17beta-Estradiol therapy reversed these effects. Chronic tamoxifen treatment exerted estrogen-like actions by reversing ovariectomy-induced enhancement of vessel tone without antagonizing the effect of chronic 17beta-estradiol treatment. Ovariectomy enhanced the relaxing potency of nicardipine, and 17beta-estradiol treatment prevented this effect. Acute exposure to 10(-9) mol/L 17beta-estradiol or 10(-8) mol/L tamoxifen did not modulate contractions in rings from nonoperated female rats. In conclusion, ovariectomy differentially enhances agonist-induced cerebrovascular tone, an effect that was reversed by estro




Angiogenesis. 2003;6(4):271-81.
17 beta -estradiol-mediated vessel assembly and stabilization in tumor angiogenesis requires TGF beta and EGFR crosstalk.

Soares R, Guo S, Gartner F, Schmitt FC, Russo J.

IPATIMUP, Institute of Molecular Pathology and Immunology of the University of Porto, Porto, Portugal. raquel.soarepatimup.pt

It is widely established that angiogenesis is required during tumor progression. Emerging data, suggests that estrogens can mediate endothelial proliferation and differentiation. We investigated the role of estrogens in the formation and stabilization of capillary-like structures, and identified 17 beta -estradiol-driven pathways involved in vessel assembly. We show that estrogens induce MCF7 breast cancer cells to secrete TGF beta 1. In addition, TGF beta cross talks with EGFR signaling pathway with concomitant up-regulation of EGFR ligand, TGF alpha, promoting cord-like formations in HUVEC cultures. The action of 17 beta -estradiol was not restricted to endothelium, since 17 beta -estradiol also stimulated recovery and migration of a smooth muscle cell line (FLTR) to injured areas again by the cross talk between these two signaling pathways. Finally, given the relevant role of 17 beta -estradiol in vessel stabilization, co-cultures of HUVEC and FLTR cells were established in the presence of 17 beta -estradiol or TGF beta 1. By blocking TGF beta or EGFR signaling, we demonstrate that 17 beta -estradiol promoted vessel stabilization through the interplay of TGF beta 1 and EGFR signaling transduction pathways. Our data suggest that estrogen mediates endothelial cell stabilization and vessel assembly. These vessel protective effects involve TGF beta 1 and EGFR signaling transduction pathways.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15166495&dopt=Abstract estradiol




J Steroid Biochem Mol Biol. 2002 Oct;82(2-3):263-8.
Estradiol stimulates expression of two human prolactin receptor isoforms with alternative exons-1 in T47D breast cancer cells.

Leondires MP, Hu ZZ, Dong J, Tsai-Morris CH, Dufau ML.

National Institute of Child Health and Human Development, Section Molecular Endocrinology, Endocrinology and Reproduction Research Branch, National Institutes of Health, Bethesda, MD 20892-4510, USA.

Human prolactin receptor (hPRLR) expression is regulated by estradiol-17beta (E(2)) in vivo in animal tissues, and in vitro in normal human endometrial cells and in MCF7 human breast cancer cells. The objective of this study was to determine the effect of E(2) on the expression of two recently described hPRLR isoforms with distinct exons-1, hE1(3) and hE1(N1) that are transcribed from the generic hPIII promoter, also present in the rat and mouse, and the human-specific promoter hP(N1), respectively. Also, to determine the effect of estradiol on the hPIII promoter activity in cancer cells. T47D breast cancer cells were examined using quantitative competitive RT-PCR for the level of expression of two alternative non-coding exon-1 transcripts, hE1(3) and hE1(N1) following incubation with E(2) in presence or absence of the E(2) receptor antagonist ICI 182,780. The effects of estradiol were also evaluated in cells transiently transfected with constructs of hPIII promoter luciferase reporter gene. E(2) significantly increased the expression of both hPRLR mRNA transcripts, hE1(3) and hE1(N1). In transfection studies E(2) activated the hPIII promoter. This effect of estradiol was markedly inhibited by coincubation with the E(2) receptor antagonist. Our results demonstrate a stimulatory effect of estradiol on the expression of hPRLR mRNA species with alternative exons-1, hE1(3) and hE1(N1) possibly through activation of their corresponding promoters. The lack of a formal ERE in these promoters suggested that the effect of estradiol is mediated through association of the activated ER wi




J Cell Physiol. 2004 Aug;200(2):253-62.
A low dose of daidzein acts as an ERbeta-selective agonist in trabecular osteoblasts of young female piglets.

De Wilde A, Lieberherr M, Colin C, Pointillart A.

Laboratoire de Nutrition et de Securite Alimentaire, Institut National de la Recherche Agronomique, Jouy-en-Josas, France.

The role of estrogens and estrogen-like molecules, including isoflavones, in regulating bone cell activities is essential in understanding the etiology and treatment of post-menopausal osteoporosis. Although estrogen replacement (HRT) has been the main therapy used to prevent and treat osteoporosis, there are concerns about its safety. Isoflavones have attracted attention to their potential roles in osteoporosis prevention and treatment. We have compared the effects of the isoflavone daidzein (1 nM), which has no effect on tyrosine kinases, and 17beta-estradiol (1 nM) on the development and function of cultured osteoblasts isolated from long bones of young female piglets. Daidzein increased ALP activity, osteocalcin secretion, and mineralization, while E2 increased only ALP activity. The content of ERbeta and osteoprotegerin secretion by control cells gradually increased during osteoblast differentiation, whereas the ERalpha and RANK-L content decreased. Daidzein enhanced only the nuclear ERbeta whereas estradiol increased both ERalpha and ERbeta. Daidzein and estradiol increased osteoprotegerin and RANK-L secretion. Daidzein had a more pronounced effect than did estradiol. Daidzein and estradiol increased the membrane content of RANK-L and the nuclear content of runx2/Cbfa1. Daidzein enhanced the nuclear content of progesterone and vitamin D receptors but not as much as did estradiol. All the effects of daidzein were blocked by ICI 182,780. We conclude that a low concentration of daidzein may exert its anti-resorptive action by increasing the activity of porcine mature osteoblasts via ERbeta, by regulating runx2/Cbfa1 production, and by stimulating the secretion of key pro




Mar Environ Res. 2004 Aug-Dec;58(2-5):443-6.
Effects of 17beta-estradiol exposure in the mussel Mytilus galloprovincialis.

Janer G, Lavado R, Thibaut R, Porte C.

Environmental Chemistry Department, IIQAB.CSIC, Jordi Girona 18, 08034 Barcelona, Spain.

Mussels Mytilus galloprovincialis were exposed to different concentrations of estradiol (20, 200, and 2000 ng/l) in a semi-static regime (1-day dosing intervals) for up to 7 days in an attempt to see how mussels dealt with exogenous estrogenic compounds. Sex hormone levels were determined in whole tissue. Free-estradiol was only significantly elevated at the highest exposure dose (up to 10-fold). Most of the estradiol was in the tissues as fatty acid esters (> 78%), which sharply increased in a dose-dependent manner (from 4 ng/g in controls to 258 ng/g at the high exposure group). In contrast, neither free nor esterified testosterone levels showed significant differences between control and exposure groups. The results suggest the existence of mechanisms that allow mussels to maintain their hormonal status, and the important role that fatty acid esterification may play within those mechanisms. Synthesis and conjugation rates of estradiol were further investigated by measuring the activity of P450 aromatase, and palmitoyl-CoA:estradiol acyltransferase, in digestive gland microsomal fractions. Overall, the study contributes to the better knowledge of molluscan endocrinology, and defines new mechanisms of regulation of free steroid-levels in mussels.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15178065&dopt=Abstract estradiol




Mar Environ Res. 2004 Aug-Dec;58(2-5):463-7.
Estradiol and estriol suppress CYP1A expression in rainbow trout primary hepatocytes.

Elskus AA.

Department of Biology, 101 Morgan Building, University of Kentucky, Lexington, KY 40506-0225, USA. aelskuky.edu

Hepatic levels of the pollutant inducible enzyme, CYP1A, are strongly suppressed in spawning female fish, a phenomenon attributed to high plasma levels of the female sex steroid hormone, estradiol. To evaluate the contribution of estrogen metabolites to estradiol-mediated CYP1A regulation, we treated primary hepatocytes isolated from juvenile rainbow trout (Oncorhynchus mykiss) with vehicle, 17beta-estradiol, or the estrogen metabolite, estriol, alone and in combination with each other and with the potent CYP1A inducer, benzo[a]pyrene (B[a]P). We found dose-dependent suppression of B[a]P-induced CYP1A activity by both steroids relative to controls. At 10(-7) M doses, estradiol and estriol suppressed B[a]P-induced CYP1A activity by 3- and 2-fold, respectively. Although not statistically significant, mean basal CYP1A activity levels were 15- and 13-fold lower in estradiol and estriol treated hepatocytes, respectively, relative to vehicle treated controls. Combining doses of estradiol and estriol failed to produce synergistic suppression of either basal or B[a]P-induced CYP1A activity relative to treatment with either steroid alone. The observed suppression is well below the often strong suppression observed in spawning female fish. We conclude that factors in addition to estradiol and estriol are likely involved in producing sexual dimorphism in CYP1A expression observed in spawning fish.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15178066&dopt=Abstract estradiol




Mar Environ Res. 2004 Aug-Dec;58(2-5):489-94.
Microsomal estrogen metabolism in channel catfish.

Butala H, Metzger C, Rimoldi J, Willett KL.

Department of Chemical Engineering, University of Mississippi, University, MS 38677-1848, USA.

Our goal was to study the involvement of cytochrome P450 genes in estrogen metabolism and the extent to which the potentially carcinogenic 4-hydroxyestradiol metabolite is formed by channel catfish (Ictalurus punctatus; CC). Estradiol metabolism and ethoxyresorufin-O-deethylase (EROD) activity were assessed in several tissues from fish collected from three variably contaminated sites in the Mississippi River Delta, from laboratory control fish, and from fish exposed to 20 mg/kg benzo(a)pyrene (BaP) i.p. for 4 days. Liver EROD activity was induced by BaP, but Delta fish EROD activities were not statistically higher than activities in control fish. Gill microsomal EROD activity was also induced by BaP, but activities were 8- to 77-fold lower than those from liver. The predominant estrogen metabolites formed by CC liver, gill and gonad microsomes were 2-hydroxyestradiol and estrone as detected by GC/MS. Liver and gill 2-hydroxyestradiol formation was induced in BaP-dosed fish. The trends in hydroxyestradiol formation in field collected fish were more variable. In all fish liver microsomes there was more 2- compared to 4-hydroxyestradiol formed. However, BaP-treatment increased the 4:2 hydroxyestradiol ratio from 0.04 in control fish to 0.2 in BaP-exposed fish, suggesting that BaP induces the formation of the potentially genotoxic estrogen metabolite. No detectable 4-hydroxyestradiol was produced by gill and gonad microsomes. These results will ultimately help in determining which fish P450 genes are susceptible to environmental contamination and may be involved in estrogen genotoxicity.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15178071&dopt=Abstract estradiol




Fertil Steril. 2002 Dec;78(6):1311-3.
Exacerbation of ovarian hyperstimulation by leuprolide reveals a gonadotroph adenoma.

Castelbaum AJ, Bigdeli H, Post KD, Freedman MF, Snyder PJ.

University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6149, USA.

OBJECTIVE: To report a case of a gonadotroph adenoma diagnosed after a dramatic increase in estradiol level and ovarian hyperstimulation in response to a gonadotropin-releasing hormone agonist. DESIGN: Case report. SETTING: Outpatient practice and university hospital. PATIENT(S): A 35-year-old woman who presented with infertility, amenorrhea, and an elevated basal estradiol concentration. INTERVENTION(S): Ultrasonography, laparoscopy, endocrinologic assays, magnetic resonance imaging, transsphenoidal surgery, and immunocytochemical staining. MAIN OUTCOME MEASURE(S): Ultrasonography and laparoscopy demonstrated bilaterally enlarged ovaries containing multiple preovulatory follicles, similar in appearance in those women undergoing controlled ovarian hyperstimulation with exogenous FSH. The serum estradiol level was moderately elevated, the FSH level was within the normal range, and LH was suppressed. Administration of leuprolide acetate resulted in very elevated estradiol concentrations and even larger ovarian cysts. Magnetic resonance imaging demonstrated a sellar mass. Examination of the tissue excised by transsphenoidal excision of the mass showed a pituitary adenoma that stained strongly for FSH. RESULT(S): Regular menses resumed soon after excision of the gonadotroph adenoma, followed by a spontaneous pregnancy. CONCLUSIONS: Gonadotroph adenoma should be suspected in a reproductive age woman with oligomenorrhea or amenorrhea, infertility, multiple preovulatory follicles, and a persistently elevated serum estradiol concentration. Exacerbation of the ovarian hyperstimulation in response to a gonadotropin-releasing hormone agonist in this setting also strongly suggests a gonadotroph adenoma but can be avoided by recogni



Steroids. 2004 Apr;69(4):255-61.
A gas chromatography/mass spectrometry assay to measure estradiol, catecholestradiols, and methoxyestradiols in plasma.

Zacharia LC, Dubey RK, Jackson EK.

Department of Medicine, Center for Clinical Pharmacology, University of Pittsburgh Medical Center, 623 Scaife Hall, 3550 Terrace Street, Pittsburgh, PA 15261, USA. lczstitt.edu

We have developed a gas chromatography/mass spectrometry (GC/MS) assay to measure 17beta-estradiol (E) and its biologically active metabolites 2-hydroxyestradiol (2OHE) and 4-hydroxyestradiol (4OHE), and 2-methoxyestradiol (2MEOE) and 4-methoxyestradiol (4MEOE) in rat plasma. All analytes are well separated and show a linear relationship between concentration (0.25-5 pg/microl) and signal, and coefficients of variation (CVs) are low. Intra-assay CV for the lowest quality control samples (QCs) (0.375 pg/microl) were on average for 17beta-estradiol 20.5%, for 2-hydroxyestradiol 15.6%, for 4-hydroxyestradiol 16.5%, for 2-methoxyestradiol 16.5%, and for 4-methoxyestradiol 11.5%. The inter-assay CVs for the lowest QCs were for 17beta-estradiol 12.1%, for 2-hydroxyestradiol 7.1%, for 4-hydroxyestradiol 15.5%, for 2-methoxyestradiol 16.7%, and for 4-methoxyestradiol 9.7%. The highest sensitivity for this assay was observed for hydroxyestradiols followed by the methoxyestradiols and 17beta-estradiol. In summary, we describe a convenient, sensitive, and specific assay to measure 17beta-estradiol and its biologically active metabolites.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15183691&dopt=Abstract estradiol [PubMed - in process]