Gynecol Endocrinol. 2001 Aug;15(4):312-20.
Effects of 17 beta-estradiol and trimegestone alone, and in combination, on the bone and uterus of ovariectomized rats.

Lepescheux L, Secchi J, Gaillard-Kelly M, Miller P.

Aventis Pharma, 102 Route de Noisy, 93235 Romainville, France.

Trimegestone is a novel norpregnane progestin, which is being developed, in combination with 17 beta-estradiol, for the treatment of menopausal symptoms and prevention of postmenopausal osteoporosis. A model of osteoporosis in the ovariectomized rat has been used to evaluate the effects of 17 beta-estradiol and trimegestone, alone and in combination, on bone and uterus in these animals. Two treatment protocols were investigated, preventive with treatment starting immediately after ovariectomy and curative with treatment starting 1 or 6 months after ovariectomy. 17 beta-Estradiol was administered subcutaneously at a dose of 10 micrograms/kg/day with trimegestone or norethisterone being administered orally at a dose of 1 mg/kg/day; treatment was given 5 days per week. Treatment on both protocols was for 6 months. Given alone, 17 beta-estradiol maintained bone mass, either partially or completely, when given on the preventive protocol, or on the curative protocol with treatment starting 1 month after ovariectomy; it did not restore bone mass when given on the curative protocol with 6 months lapsing between ovariectomy and start of treatment. Trimegestone did not block the beneficial effects of 17 beta-estradiol on bone. 17 beta-Estradiol induced uterine hypertrophy on all these protocols and this was blocked completely by trimegestone. Trimegestone administered alone had no effect on bone or uterus but, when given in combination with 17 beta-estradiol, it did not inhibit the effect of 17 beta-estradiol in maintaining bone mass but completely blocked its uterotropic effect. Norethisterone at a similar dose did not inhibit the effects of 17 beta-estradiol on bone but also did not block its uterotropic effect.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=115&dopt=Abstract




Arch Cardiol Mex. 2001 Apr-Jun;71(2):114-20.
[17-beta estradiol induces type III nitric oxide synthase expression in cultured endothelial cells]

[Article in Spanish]

Jimenez GM, Ceja Ochoa I, Hernandez Perez A, Escalante Acosta B.

Departamento de Fisiologia, Escuela Nacional de Ciencias Biologicas del IPN, No. 2508, Col. Sn. Pedro Zacatenco, Mexico D.F.

It has been suggested that the low incidence of cardiovascular diseases in premenopausal women, compared with that in men of the same age, is related to the interaction between the nitric oxide (NO) pathway and estrogens. The aim of the present work was to characterize the mechanism by which 17-beta estradiol produces an increment in NO release in cultured endothelial cells. Treatment of cells with 17-beta estradiol significantly increased the amount of nitrites delivered into the culture medium, compared with that from cells without estrogenic treatment. This effect was blocked by the antagonist of estrogen receptors, tamoxifen. By Western blot, it was shown that 17-beta estradiol significantly increased the amount of eNOS in treated cells, compared with that from their respective control cells. Moreover, the acetylcholine-induced release of nitrites in cells treated with 17-beta estradiol was higher than nitrite production induced by the same dose of acetylcholine in control cells. In conclusion, our data underline the physiological role of 17-beta estradiol, which promotes the increase in eNOS expression, potentiating the effects of vascular agonists that release nitric oxide, suggesting a cardiovascular protective role by estrogens.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11565302&dopt=Abstract estradiol




J Steroid Biochem Mol Biol. 2001 Aug;78(2):113-22.
Structure-effect relationship in the induction of mitotic phase-specific abnormality of centrosome integrity and multipolar spindles by steroidal estrogens and their derivatives in cultured mammalian cells.

Ochi T, Oda T.

Department of Toxicology and Environmental Health, Faculty of Pharmaceutical Sciences, Teikyo University, Sagamiko, 199-0195, Kanagawa, Japan. tkfmochharm.teikyo-u.ac.jp

In order to determine the structure-effect relationship in the induction of centrosome disintegrity (abnormality of gamma-tubulin signals) and multipolar spindles in a cultured fibroblast cell line V79 by steroidal estrogens, the activities of various estrogens and their derivatives were investigated. Induction of centrosome disintegrity by estrogens was specific in cells in the mitotic phase and was not observed in interphase cells. The centrosome disintegrity induced 24 h after exposure to estrogens was accompanied by the appearance of multinucleated cells, but the microtubule network was organized. The rank order of potency of estrogens in inducing mitotic phase-specific centrosome disintegrity and multipolar spindles was as follows: 2-methoxyestradiol>dihydroequilin 3-methyl ether=equilin 3-methyl ether>17alpha-estradiol>17beta-estradiol 3-methyl ether=17beta-estradiol>dihydroequilin>estrone 3-methyl ether. Equilin and estrone were not effective in causing centrosome disintegrity. These results suggest that the 17-hydroxyl group, irrespective of whether it is the sterically alpha or beta form, is necessary for estradiol and dihydroequilin to cause centrosome disintegrity and that O-methylation at the C-3 position was effective for equilin and dihydroequilin in enhancing the centrosome abnormality. 2-Methoxyestradiol was the most potent inducer of the centrosome disintegrity among the tested compounds and caused the induction of multiple signals of gamma-tubulin, including more than five signals.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11566435&dopt=Abstract estradiol [PubMed - indexed for MEDLIN




J Steroid Biochem Mol Biol. 2001 Aug;78(2):145-56.
2-Methoxymethylestradiol: a new 2-methoxy estrogen analog that exhibits antiproliferative activity and alters tubulin dynamics.

Brueggemeier RW, Bhat AS, Lovely CJ, Coughenour HD, Joomprabutra S, Weitzel DH, Vandre DD, Yusuf F, Burak WE Jr.

Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, The Ohio State University, 500 West 12th Avenue, Columbus, OH 43210-1291, USA. brueggemeier.su.edu

An estradiol metabolite, 2-methoxyestradiol (2-MeOE(2)), has shown antiproliferative effects in both hormone-dependent and hormone-independent breast cancer cells. Previously, a series of 2-hydroxyalkyl estradiol analogs had been synthesized in our laboratories as potential probes for comparison of estrogen receptor (ER)-mediated versus non-ER-mediated effects in breast cancer cells. A methoxy derivative of 2-hydroxymethyl estradiol was prepared for biological evaluation and comparison with 2-MeOE(2). Estrogenic activity of the synthetic analogs was evaluated in two ways, one by examining affinity of the analogs for the estrogen receptor in MCF-7 cells and the other by examining the ability of the analogs to induce estrogen-responsive gene expression. The analog, 2-methoxymethyl estradiol (2-MeOMeE(2)), demonstrated weak affinity for the estrogen receptor (0.9% of estradiol) and weak ability to stimulate estrogen-induced expression of the pS2 gene (0.02% of estradiol). Antitumor activity was evaluated both in vitro and in vivo. The steroidal nucleus seems to be an attractive target for developing novel tubulin polymerization inhibitors. Additionally, such steroidal compounds may have low toxicity compared to the natural products known to interact with tubulin. Interestingly, 2-MeOMeE(2) inhibited tubulin polymerization in vitro at concentrations of 1 and 3 microM and was more effective than 2-MeOE(2). In cells, 2-MeOMeE(2) was effective in suppressing growth and inducing cytotoxicity in MCF-7 and MDA-MB-231 breast cancer cells. The cytotoxic ef




Toxicol In Vitro. 2001 Aug-Oct;15(4-5):489-95.
Toxic effects of the mycotoxin zearalenone and its derivatives on in vitro maturation of bovine oocytes and 17 beta-estradiol levels in mural granulosa cell cultures.

Minervini F, Dell'Aquila ME, Maritato F, Minoia P, Visconti A.

Institute of Toxins and Mycotoxins, CNR, Viale Einaudi 51, 70125 Bari, Italy. itmpfm1rea.cnr.it

Moulds parasites of livestock foodstuffs alter the quality of grains by synthesizing mycotoxins. Zearalenone (ZEA) and its derivatives (alpha- and beta-zearalenol, zeranol, taleranol and zearalanone) are produced by fungi of the genus Fusarium and, after ingestion via contaminated cereals, may lead to fertility disturbances and other reproductive pathologies. Zearalenone, alpha-zearalenol and zearalanone were tested, at levels ranging from 0.3 to 30 microg/ml, in order to evaluate the effect on the in vitro maturation (IVM) rate of bovine oocytes and on the formation of 17 beta-estradiol in supernatants of mural granulosa cells (GC) cultures. These compounds induced dose-dependent oocyte maturation delay and chromatin abnormalities. Maturation of oocytes to metaphase II (M II) was inhibited in oocytes cultured in the presence of 30 microg/ml ZEA, alpha-zearalenol or zearalanone, with a significant increase in chromatin abnormalities occurring in the presence of ZEA (P<0.05) and alpha-zearalenol (P< 0.001). In preliminary trials on 17 beta-estradiol formation, at the same testing concentration, higher levels of 17 beta-estradiol were found in the presence of alpha-zearalenol (mean value 1.6 ng/ml) with respect to ZEA and zearalanone (mean estradiol concentrations of 0.06 and 0.5 ng/ml, respectively). These data demonstrate a negative effect of ZEA and its derivatives on meiotic progression of bovine oocytes, possibly attributable to a toxic mechanism not related to the binding affinity of these compounds to estrogen receptor sites, and support previous observations that alpha-zearalenol acts as a stronger estrogenic inducer




J Clin Invest. 2003 May;111(9):1319-27.
A functional androgen receptor is not sufficient to allow estradiol to protect bone after gonadectomy in estradiol receptor-deficient mice.

Sims NA, Clement-Lacroix P, Minet D, Fraslon-Vanhulle C, Gaillard-Kelly M, Resche-Rigon M, Baron R.

Department of Orthopaedics, Yale University School of Medicine, New Haven, Connecticut 06520-8044, USA.

Although the role of estradiol in maintaining bone mass is well established, the relative contributions of the estradiol receptors ERalpha and ERbeta and of the androgen receptor (AR) remain controversial. To determine the role of ERalpha-mediated, ERbeta-mediated, and non-ER-mediated mechanisms in maintaining bone mass, gonadectomy and estradiol treatment were studied in ER-knockout mice. Estradiol treatment of ovariectomized ERalphabeta(-/-) mice failed to prevent bone loss, precluding significant effects of estradiol on bone through non-ER-signaling pathways. In contrast, estradiol prevented ovariectomy-induced bone loss in ERbeta(-/-) mice, as in WT males and females, indicating that ERalpha is the major mediator of estradiol effects in bone. No response of bone to estradiol was detected in orchidectomized ERalpha(-/-) mice, suggesting estradiol cannot protect bone mass via the AR in vivo. In contrast to female ERalphabeta(-/-) and male ERalpha(-/-) mice, female ERalpha(-/-) mice were partially protected against ovariectomy-induced bone loss by estradiol, confirming that ERbeta mediates estradiol effects in bone, but only in females and with a lower efficacy than ERalpha. We conclude that ERalpha is the main effector of estradiol's protective function in bone in both male and female mice, and that, in its absence, AR is not sufficient to mediate this response.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12727923&dopt=Abstract estradiol




Oncogene. 2001 Sep 6;20(39):5420-30.
Membrane-associated binding sites for estrogen contribute to growth regulation of human breast cancer cells.

Marquez DC, Pietras RJ.

Department of Medicine, Division of Hematology-Oncology, UCLA School of Medicine, Los Angeles, California, 90095-1678, USA.

Membrane-associated binding sites for estrogen may mediate rapid effects of estradiol-17beta that contribute to proliferation of human breast cancers. After controlled homogenization and fractionation of MCF-7 breast cancer cells, the bulk of specific estradiol binding is found in nuclear fractions. However, a significant portion of specific, high-affinity estradiol-17beta binding-sites are also enriched in plasma membranes. These estradiol binding-sites co-purify with 5'-nucleotidase, a plasma membrane-marker enzyme, and are free from major contamination by cytosol or nuclei. Electrophoresis of membrane fractions allowed detection of a primary 67-kDa protein and a secondary 46-kDa protein recognized by estradiol-17beta and by a monoclonal antibody directed to the ligand-binding domain of the nuclear form of estrogen receptor. Estrogen-induced growth of MCF-7 breast cancer cells in vitro was blocked by treatment with the antibody to estrogen receptor and correlated closely with acute hormonal activation of mitogen-activated protein kinase and Akt kinase signaling. Estrogen-promoted growth of human breast cancer xenografts in nude mice was also significantly reduced by treatment in vivo with the estrogen receptor antibody. Thus, membrane-associated forms of estrogen receptor may play a role in promoting intracellular signaling for hormone-mediated proliferation and survival of breast cancers and offer a new target for antitumor therapy.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11571639&dopt=Abstract estradiol




Br Poult Sci. 2001 Sep;42(4):530-5.
Effect of exogenous oestradiol and lighting regime on age at first egg in domestic pullets.

Lewis PD, Dunn IC, Perry GC, Morris TR, Sharp PJ.

School of Veterinary Science, University of Bristol, Langford, England. petelatford.demon.co.uk

1. Groups of ISA Brown pullets were transferred from 8- to 16-h photoperiods at 34, 44 or 54 d. In each group, 12 birds were injected on alternate days over a 12-d period starting 6 d before the change in photoperiod with beta-oestradiol-3-benzoate (1 mg/kg body weight) or with arachis oil vehicle (controls). Short-day controls were similarly injected from 28 to 40 d. Long-day (16 h) controls were also included in the trial but were not injected. Age at first egg (AFE) was recorded and plasma luteinising hormone (LH) concentrations were measured around the time of oestradiol treatment. 2. Mean AFE for birds photostimulated at 34 d was not significantly different from short-day controls. Birds photostimulated at 44 and 54 d matured at similar ages but 3 weeks earlier than short-day controls (P<0.05). 3. There was a tendency for oestradiol to advance AFE for birds photostimulated at 34 d (P=0.15) but to delay AFE following photostimulation at 44 d (P=0.23). Oestradiol significantly delayed AFE for the birds photostimulated at 54 d (P=0.01). 4. Plasma LH levels during 6 d of oestradiol injection but before transfer from 8- to 16-h photoperiods tended to fall between 28 and 34 d, were relatively constant between 38 and 44 d, but declined significantly between 48 and 54 d. Following photostimulation at 34 d, increases in plasma LH levels for oestradiol-injected birds were significantly greater than for controls. Oestradiol treatment had no significant effect on changes in plasma LH concentrations after photostimulation at 44 or 54 d. 5. This trial confirms previous work showing that pullets are unresponsive to photostimulation before 6 weeks of age. It also demonstrates that raising circulating oestrogen levels by in




Hum Reprod. 2001 Oct;16(10):2114-7.
Colour Doppler analysis of peri-implantation utero-ovarian haemodynamics in women with excessively high oestradiol concentrations after ovarian stimulation.

Basir GS, Lam TP, Chau MT, Ng EH, O WS, Ho PC.

Department of Obstetrics and Gynaecology, Queen Mary Hospital, The University of Hong Kong, Pokfulam, Hong Kong.

BACKGROUND: Gonadotrophins are used in many assisted reproduction units to achieve a better success rate by increasing the number of replaced embryos. However, high oestradiol concentrations are associated with altered physiological functions and its complications. We investigated whether high oestradiol concentrations (> or =20 000 pmol/l) after ovarian stimulation in infertile women would affect the uterine haemodynamics at the time of embryo transfer. METHODS: Colour Doppler indices of utero-ovarian arteries and endometrial colour signals were measured. Fifty-eight women undergoing ovarian stimulation for IVF were classified according to serum oestradiol concentrations on the day of human chorionic gonadotrophin injection into moderate responders (oestradiol <20 000 pmol/l; n = 39) and high responders (oestradiol > or =20 000 pmol/l; n = 19). RESULTS: Haemodynamic parameters were significantly lower in high responders; the uterine arterial pulsatility index (PI) and resistance index (RI) were (median; range) 1.87 (0.84-2.82) and 0.79 (0.57-0.90) respectively; ovarian artery PI was 0.57 (0.40-1.12) and RI was 0.43 (0.33-0.64). In moderate responders the uterine PI and RI were 2.63 (1.46-5.92) and 0.88 (0.77-1.10) respectively. Ovarian PI was 0.81 (0.32-3.72) and RI was 0.55 (0.23-0.97). The number of women showing endometrial colour signals was significantly lower in high responders (63%) than in moderate responders (92%) (P < 0.05). A further increase in oestradiol (> or =25 000 pmol/l; n = 8) showed significantly (P = 0.03) fewer endometrial colour signals [1.5 (0-8)] compared with moderate responders [4 (0-14)]. CONCLUSI