Mar Environ Res. 2000 Jul-Dec;50(1-5):201-6.
Determining the sensitive developmental stages of intersex induction in medaka (Oryzias latipes) exposed to 17 beta-estradiol or testosterone.
Koger CS, Teh SJ, Hinton DE.
Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA.
Certain environmentally persistent compounds can adversely affect reproduction by acting as steroid hormone agonists or antagonists. The goal of the present study was to determine the developmental stage most susceptible to exogenous hormone (estradiol and testosterone) exposure using a small teleost model. In the first (pilot study) of two experiments, medaka (Oryzias latipes), at varying developmental stages, were bath-exposed to 5 micrograms/l 17 beta-estradiol for 24 h. At 5 months of age, fecundity, fertility and embryo and larval viability (reproductive success) were investigated in control and exposed groups. Fish at 1, 1.5, 2 and 5.5 months of age were also sampled, processed and examined histologically for gonadal alteration. No significant differences in mortality, gonadal morphology, body weight, sex-ratio or time to maturity were seen between control and exposed fish. At 5 months, however, when exposure groups were compared to controls, significant differences were seen in reproductive success and viability of offspring. A second experiment exposed embryo stage 10, and 1-, 7- and 21-day-old larvae for 6 days to 15 micrograms/l 17 beta-estradiol or 100 micrograms/l testosterone. No significant differences were seen at 5 months in mortality, body weight, or time to sexual maturity. However, sex-ratios were significantly biased toward female in the stage 10, 1- and 7-day post-hatch estradiol exposure groups. No significant changes in sex-ratio were associated with testosterone exposure at any developmental stage. Further, intersex gonads were observed in fish from all groups exposed to 15 micrograms/l estradiol. Only those fish exposed as
Xenobiotica. 2001 Mar;31(3):163-76.
Specificity of 17beta-oestradiol and benzo[a]pyrene oxidation by polymorphic human cytochrome P4501B1 variants substituted at residues 48, 119 and 432.
Shimada T, Watanabe J, Inoue K, Guengerich FP, Gillam EM.
Osaka Prefectural Institute of Public Health, Japan. shimadph.pref.osaka.jp
1. Eight human cytochrome P4501B1 (CYP1B1) allelic variants, namely Arg48 Ala119 Leu432, Arg48 Ala119 Val432 Gly48 Ala119 Leu432, Gly48 Ala119 Val432, Arg48 Ser119 Leu432, Arg48 Ser119 Val432, Gly48 Ser119 Leu432 and Gly48 Ser119 Va1432 (all with Asn453), were expressed in Escherichia coli together with human NADPH-P450 reductase and their catalytic specificities towards oxidation of 17beta-oestradiol and benzo[a]pyrene were determined. 2. All of the CYP1B1 variants expressed in bacterial membranes showed Fe2+.CO versus Fe2+ difference spectra with wavelength maxima at 446 nm and they reacted with antibodies raised against recombinant human CYP1B1 in immunoblots. The ratio of expression of the reductase to CYP1B1 in these eight preparations ranged from 0.2 to 0.5. 3. CYP1B1 Arg48 variants tended to have higher activities for 17beta-oestradiol 4-hydroxylation than Gly48 variants, although there were no significant variations in 17beta-oestradiol 2-hydroxylation activity in these eight CYP1B1 variants. Interestingly, ratios of formation of 17beta-oestradiol 4-hydroxylation to 2-hydroxylation by these CYP1B1 variants were higher in all of the Val432 forms than the corresponding Leu432 forms. 4. In contrast, Leu432 forms of CYP1B1 showed higher rates of oxidation of benzo[a]pyrene (to the 7,8-dihydoxy-7,8-dihydrodiol in the presence of epoxide hydrolase) than did the Val432 forms. 5. These results suggest that polymorphic human CYP1B1 variants may cause some altered catalytic specificity with 17beta-oestradiol and benzo[a]pyrene and may influence susceptibilities of individuals towards endogenous and exogenous carcinogens.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11465393&dopt=Abstract estradiol [PubMed - indexed for MEDLI
Biol Reprod. 2001 Aug;65(2):622-7.
2-Methoxyestradiol, an endogenous estradiol metabolite, differentially inhibits granulosa and endothelial cell mitosis: a potential follicular antiangiogenic regulator.
Shang W, Konidari I, Schomberg DW.
Department of Obstetrics and Gynecology, Duke University Medical Center, Durham, North Carolina 27710, USA.
2-Methoxyestradiol (2-ME) is an estradiol metabolite with antiangiogenic and antitumor activity. It is formed by granulosa cell (GC) catechol-O-methyltransferase activity and is present in the normal follicle at high concentrations. In this unique microenvironment, it may regulate selected cell types via autocrine and/or paracrine action. To assess the possibility that 2-ME or estradiol might exert differential mitotic and/or apoptotic effects on endothelial cells and GCs, we compared their actions on primary cultures of hormone- and/or growth factor-stimulated porcine GCs (pGCs) as well as two types of endothelial cells, primary cultures of porcine endothelial cells (pECs), and a spontaneously transformed rabbit endothelial vascular cell (REVC) line. The 2-ME, but not estradiol, dose dependently suppressed tritiated thymidine ((3)H-T) incorporation into epidermal growth factor (EGF)-stimulated REVCs and EGF/insulin (INS)-stimulated pECs. In contrast, 2-ME did not attenuate incorporation in FSH/INS-stimulated pGCs. It reduced incorporation by approximately 50% in EGF/INS-stimulated pGCs, indicating that responsiveness to 2-ME in normal cells can be modulated by hormone and growth factor treatment. Estradiol was not antimitotic to pGCs. As indicated by 4',6-diamido-2-phenylindole hydrochloride nuclear staining, estradiol was nonapoptotic in either cell type, and 2-ME significantly increased apoptosis of REVCs, but not of pGCs. In a cell migration assay, REVC movement was attenuated by 2-ME, but not by estradiol. In summary, the results show that antimitotic as well as proapoptotic responses to 2-ME vary with cell type and, in the case of pGC anti
J Biol Chem. 2003 Jan 24;278(4):2118-23. Epub 2002 Nov 12.
Src kinase mediates phosphatidylinositol 3-kinase/Akt-dependent rapid endothelial nitric-oxide synthase activation by estrogen.
Haynes MP, Li L, Sinha D, Russell KS, Hisamoto K, Baron R, Collinge M, Sessa WC, Bender JR.
Section of Cardiovascular Medicine, Department of Pharmacology, Boyer Center for Molecular Medicine, Yale University School of Medicine, New Haven, Connecticut 06536, USA.
17beta-Estradiol activates endothelial nitric oxide synthase (eNOS), enhancing nitric oxide (NO) release from endothelial cells via the phosphatidylinositol 3-kinase (PI3-kinase)/Akt pathway. The upstream regulators of this pathway are unknown. We now demonstrate that 17beta-estradiol rapidly activates eNOS through Src kinase in human endothelial cells. The Src family kinase specific-inhibitor 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (PP2) abrogates 17beta-estradiol- but not ionomycin-stimulated NO release. Consistent with these results, PP2 blocked 17beta-estradiol-induced Akt phosphorylation but did not inhibit NO release from cells transduced with a constitutively active Akt. PP2 abrogated 17beta-estradiol-induced activation of PI3-kinase, indicating that the PP2-inhibitable kinase is upstream of PI3-kinase and Akt. A 17beta-estradiol-induced estrogen receptor/c-Src association correlated with rapid c-Src phosphorylation. Moreover, transfection of kinase-dead c-Src inhibited 17beta-estradiol-induced Akt phosphorylation, whereas constitutively active c-Src increased basal Akt phosphorylation. Estrogen stimulation of murine embryonic fibroblasts with homozygous deletions of the c-src, fyn, and yes genes failed to induce Akt phosphorylation, whereas cells maintaining c-Src expression demonstrated estrogen-induced Akt activation. Estrogen rapidly activated c-Src inducing an estrogen receptor, c-Src, and P85 (regulatory subunit of PI3-kinase) complex formation. This complex formation results in the successive activation of PI3-kinase, Akt, and eN
Braz J Med Biol Res. 2001 Aug;34(8):1015-22.
Effect of 17beta-estradiol or alendronate on the bone densitometry, bone histomorphometry and bone metabolism of ovariectomized rats.
da Paz LH, de Falco V, Teng NC, dos Reis LM, Pereira RM, Jorgetti V.
Departamento de Reumatologia, Faculdade de Medicina, Universidade de Sao Paulo, Av. Dr. Arnaldo, 01246-930 Sao Paulo SP, Brazil. vandajosp.br
The objective of the present study was to evaluate the effect of 17beta-estradiol or alendronate in preventing bone loss in 3-month-old ovariectomized Wistar rats. One group underwent sham ovariectomy (control, N = 10), and the remaining three underwent double ovariectomy. One ovariectomized group did not receive any treatment (OVX, N = 12). A second received subcutaneous 17beta-estradiol at a dose of 30 microg/kg for 6 weeks (OVX-E, N = 11) and a third, subcutaneous alendronate at a dose of 0.1 mg/kg for 6 weeks (OVX-A, N = 8). Histomorphometry, densitometry, osteocalcin and deoxypyridinoline measurements were applied to all groups. After 6 weeks there was a significant decrease in bone mineral density (BMD) at the trabecular site (distal femur) in OVX rats. Both alendronate and 17beta-estradiol increased the BMD of ovariectomized rats, with the BMD of the OVX-A group being higher than that of the OVX-E group. Histomorphometry of the distal femur showed a decrease in trabecular volume in the untreated group (OVX), and an increase in the two treated groups, principally in the alendronate group. In OVX-A there was a greater increase in trabecular number. An increase in trabecular thickness, however, was seen only in the OVX-E group. There was also a decrease in bone turnover in both OVX-E and OVX-A. The osteocalcin and deoxypyridinoline levels were decreased in both treated groups, mainly in OVX-A. Although both drugs were effective in inhibiting bone loss, alendronate proved to be more effective than estradiol at the doses used in increasing bone mass.
Bone. 2001 Jul;29(1):30-4.
The effect of 17beta-estradiol on production of cytokines in cultures of peripheral blood.
Rogers A, Eastell R.
Bone Metabolism Group, Section of Medicine, Division of Clinical Sciences (North), University of Sheffield, Sheffield, UK.
Estrogen's action on bone may be mediated by cytokines produced by monocytes. We have reported a decreased ratio of interleukin-1beta (IL-1beta) to interleukin-1 receptor antagonist (IL-1ra) produced by whole blood cultures in vivo in women taking hormone replacement therapy (HRT). Also, one study has shown an effect of estradiol on tumor necrosis factor-alpha (TNF-alpha) secretion by separated monocytes in vitro. The aim of this study was to evaluate the effect of estrogen in vitro on the secretion of cytokines using whole blood cultures. Subjects consisted of 12 healthy postmenopausal women, ages 57-69 years, 4-20 years since menopause. Cytokines IL-1beta, interleukin-1alpha (IL-1alpha), IL-1ra, interleukin-6 (IL-6), TNF-alpha, and granulocyte macrophage-colony stimulating factor (GM-CSF) were measured in unstimulated and in stimulated (500 ng/mL lipopolysaccharide [LPS]) whole blood cultures treated with 17beta-estradiol (E(2)) at concentrations of 10(-12)--10(-6) mol/L. We found significant decreases in the spontaneous secretion of IL-6, TNF-alpha, IL-1ra, IL-1beta, and ratio of IL-1beta/IL-1ra compared with control, at physiological concentrations of E(2). The action of E(2) was blocked by the use of the antiestrogen ICI 182780 in coculture. A decrease in cytokine secretion was not observed when the inactive form of estrogen, 17alpha-estradiol, was used in place of 17beta-estradiol. GM-CSF and IL-1alpha were not detectable in unstimulated cultures. Cytokine levels measured in stimulated cultures were not attenuated by treatment with E(2). We conclude that E(2) inhibits the spontaneous secretion of cytokines measured in whole blood cultures at physiological concentrations, and that the powerful stimulatory effect of
Clin Exp Pharmacol Physiol. 2001 Aug;28(8):637-42.
Effect of epomediol on ethinyloestradiol-induced changes in bile acid and cholesterol metabolism in rats.
Cuevas MJ, Mauriz JL, Almar M, Collado PS, Gonzalez-Gallego J.
Department of Physiology, University of Leon, University Campus, 24071 Leon, Spain.
1. Epomediol is a terpenoid compound that has been reported to stimulate bile acid synthesis and to reverse 17alpha- ethinyloestradiol-induced cholestasis. The aim of the present study was to investigate the contribution of changes in bile acid and cholesterol metabolism to the protective effects of epomediol in ethinyloestradiol-treated rats. Animals received epomediol for 5 days at 100 mg/kg daily, i.p., ethinyloestradiol for 5 days at 5 mg/kg, s.c., or a combination of both drugs. 2. When compared with control animals, epomediol treatment resulted in a significant increase in bile flow (+42%) and in the secretion of bile acids (+74%) and cholesterol (+42%). Ethinyloestradiol administration caused a significant decrease in bile flow (-43%), bile acid secretion (-37%) and cholesterol secretion (-45%). Bile flow, bile acid secretion and cholesterol secretion were significantly increased in animals receiving ethinyloestradiol plus epomediol compared with ethinyloestradiol-treated rats (+13, +29 and +31%, respectively). 3. Both cholesterol 7alpha-hydroxylase and hydroxy-3- methylglutaryl coenzyme A reductase activities were significantly increased in epomediol-treated rats (+30 and +96%, respectively). Cholesterol 7alpha-hydroxylase activity was significantly reduced by ethinyloestradiol (-22%) and did not differ from control values in animals receiving epomediol plus ethinyloestradiol. Levels of cholesterol 7alpha-hydroxylase mRNA were elevated (+41%) by epomediol, but were not significantly modified by ethinyloestradiol or ethinyloestradiol plus epomediol. 4. It is concluded that epomediol enhances bile acid secretion by increasing the expression of cholesterol 7alpha-hydroxylase. Changes in bile acid m
Joint Bone Spine. 2003 Feb;70(1):40-5.
Bone mineral density in systemic lupus erythematosus and its relation to age at disease onset, plasmatic estradiol and immunosuppressive therapy.
Coimbra IB, Costallat LT.
Rheumatology Unit, Department of Internal Medicine, Faculty of Medical Sciences, State University of Campinas, Brazil.
OBJECTIVE: The aim of this paper was to evaluate bone mineral density (BMD) in patients with systemic lupus erythematosus (SLE), to determine the role of corticosteroids and cytotoxic drugs and to assess estrogen effect on BMD in SLE. PATIENTS AND METHODS: BMD (DEXA) at lumbar vertebrae (L2-L4) and at femoral neck was performed in 60 pre-menopausal SLE patients and in 64 controls. Estradiol level was measured in all the individuals. Age, age at disease onset, body mass index (BMI), time of disease, disease activity (SLEDAI), prednisone dose at the evaluation, total cumulative and cumulative prednisone dose in the last year and cytotoxic drugs were assessed. RESULTS: The mean plasmatic estradiol was 175.9 pg/ml in patients and 149.9 in controls. BMD was inferior in patients than that in controls (P < 0.0001). The mean current, cumulative and previous year prednisone doses were, respectively, 19.17 mg/d, 28.78 g and 5.33 g. There was no association between corticosteroids or cytotoxic drug used and low bone mass. The serum concentration of estradiol did not influence the bone mass. The BMI and age at disease onset exhibited an influence on BMD at L2. CONCLUSIONS: BMD was significantly lower in SLE patients but not related to CS (Corticosteroids)or other drugs; the estradiol in these patients had no effect on BMD. Low BMI interacting with early onset of disease might influence the probability of loss of bone mass.
Cancer Biol Ther. 2002 May-Jun;1(3):256-62.
The effects of beta-estradiol on Raf activity, cell cycle progression and growth factor synthesis in the MCF-7 breast cancer cell line.
Weinstein-Oppenheimer CR, Burrows C, Steelman LS, McCubrey JA.
Department of Microbiology ond Immunology, Brody School of Medicine at East Carolina University, Greenville, North Carolina 27858, USA.
The aim of this study was to test the hypothesis that some of the proliferative effects of steroid hormones on cancer cells are mediated by the Raf proto-oncogenes. The human breast cancer cell line MCF-7 is estrogen-receptor (ER) positive (+). NCI/ADR-RES is a human cell line lacking the estrogen receptor (ER-) that was initially named MCF-ADR. Raf-1, A-Raf and B-Raf kinase activities were examined in cell lines treated with beta-estradiol for 24 hours. Increases in Raf-1 and A-Raf activities were observed after treatment with beta-estradiol in the ER (+) MCF-7 cells but not in the ER (-) NCI/ADR-RES cells. In contrast, no significant changes in B-Raf activity were observed. Thus beta-estradiol can induce Raf-1 and A-Raf activities in ER (+) cells. In addition, beta-estradiol caused cell cycle progression in MCF-7 cells and an increased proliferative response to beta-estradiol was observed in MCF-7, which overexpressed constitutively-active Raf-1 (MCF/DeltaRaf-1). Increased mRNA levels of the ligand for the c-erb-B2 receptor, amphiregulin (ARG) were observed after beta-estradiol treatment of MCF-7 cells whereas constitutively higher levels of ARG and its receptor, c-erb-B2 mRNAs were detected in MCF/DeltaRaf-1 cells. These findings suggest that targeting Raf may prove efficacious in breast cancer therapies.
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