J Endocrinol. 2003 Nov;179(2):155-63.
N-methyl-D-aspartate receptor activity and estradiol: separate regulation of cell proliferation in the dentate gyrus of adult female meadow vole.
Ormerod BK, Falconer EM, Galea LA.
Department of Psychology and Graduate Neuroscience Program, 2136 West Mall, The University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4.
We have previously found that estradiol increases (within 4 h) but then decreases (within 48 h) cell proliferation in the dentate gyrus of adult female ovariectomized (OVX) rats and of intact meadow voles and that estradiol partially stimulates adrenal activity to suppress cell proliferation in rats. Estradiol enhances N-methyl-D-aspartate receptor (NMDAr) activity and NMDAr activation suppresses cell proliferation in the adult rodent dentate gyrus. Therefore, we tested whether estradiol alters cell proliferation in the dentate gyrus of adult OVX female meadow voles by stimulating NMDAr activity. In experiment 1, OVX females were injected with estradiol (10 micro g) or oil and then with NMDA (30 mg/kg) or vehicle 3 h later and bromodeoxyuridine 4 h later (BrdU; 50 mg/kg). Voles were perfused 1 h after BrdU injection. Relative to oil vehicle, estradiol increased (P</=0.001) and NMDA decreased (P</=0.006) labeled cell number. Coadministration of estradiol/NMDA increased labeled cell numbers relative to NMDA alone (P</=0.03), suggesting that within 4 h estradiol does not influence the effect of NMDA receptors on cell proliferation. In experiment 2, OVX females were injected with either estradiol or oil and then with either MK-801 (1 mg/kg) or vehicle 47 h later and BrdU 48 h later. The animals were perfused 1 h after BrdU was injected. Relative to oil-treated voles, estradiol-treated voles had fewer (P<0.006) and MK-801-treated voles had more labeled cells (P</=0.0001) in the dentate gyrus. However, estradiol did not appear to stimulate NMDA receptors to suppress cell proliferation because estradiol (48 h)/M
Regul Pept. 2003 Nov 15;116(1-3):155-62.
Long-term estradiol treatment improves VIP-mediated vasodilation in atherosclerotic proximal coronary arteries.
Dalsgaard T, Mortensen A, Larsen CR, Larsen JJ, Ottesen B.
Department of Obstetrics and Gynecology, Hvidovre University Hospital, Copenhagen, Denmark. torur.dalsgaaradlnet.dk
The aim of the present study was to evaluate the impact of long-term estrogen replacement therapy (ERT) on the vasodilatory effect of the two peptides vasoactive intestinal polypeptide (VIP) and pituitary adenylate cyclase activating polypeptide (PACAP) in atherosclerotic coronary and cerebral arteries.Female ovariectomized homozygous Watanabe heritable hyperlipidemic rabbits were randomized to 16 weeks treatment with 17beta-estradiol or placebo. The diet was semisynthetic, thereby avoiding the influence of phytoestrogens. Artery ring segments were mounted for isometric tension recordings in myographs. Following precontraction, the dose-response relationships for VIP and PACAP were evaluated.Treatment with 17beta-estradiol significantly improved the maximum VIP-mediated vasodilation (E(max), percentage of precontraction) in proximal coronary arteries (45.8+/-9.6% vs. 24.1+/-3.7%, p<0.05). In the same artery segment, 17beta-estradiol induced a significant decrease in the relative ratio between the repeated contractile response to potassium 30 and 120 mM (100+/-7% vs. 132+/-11%, p<0.05). For distal coronary arteries, there was a tendency to similar changes, but no statistical differences for the potassium or VIP responses in cerebral or distal coronary arteries were found between the two groups. 17beta-estradiol induced no changes in the PACAP-mediated vasodilation.These results suggest that long-term treatment with 17beta-estradiol improves the VIP-mediated but not the PACAP-mediated vasodilation in atherosclerotic proximal coronary arteries.
J Natl Cancer Inst. 2003 Nov 5;95(21):1597-608.
Paradoxical action of fulvestrant in estradiol-induced regression of tamoxifen-stimulated breast cancer.
Osipo C, Gajdos C, Liu H, Chen B, Jordan VC.
Robert H. Lurie Comprehensive Cancer Center, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
BACKGROUND: Long-term tamoxifen treatment of breast cancer can result in tamoxifen-stimulated breast cancer, in which estrogen inhibits tumor growth after tamoxifen withdrawal. We investigated the molecular mechanism(s) of estradiol-induced tumor regression by using an in vivo model of tamoxifen-stimulated human breast cancer. METHODS: Growth of parental estradiol-stimulated MCF-7E2 and long-term tamoxifen-stimulated MCF-7TAMLT xenografts in athymic mice was measured during treatment with vehicle, estradiol, estradiol plus tamoxifen, tamoxifen alone, estradiol plus fulvestrant, or fulvestrant alone. Apoptosis was detected by the terminal deoxynucleotidyltransferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) assay. Protein expression was assessed by western blot analysis. mRNA expression was assessed by real-time reverse transcription-polymerase chain reaction. All statistical tests were two-sided. RESULTS: MCF-7E2 tumor growth was stimulated by estradiol (cross-sectional area at week 13 = 1.06 cm2, 95% confidence interval [CI] = 0.82 to 1.30 cm2; P<.001) compared with control (0.06 cm2, 95%CI = -0.02 to 0.14 cm2), but tumor growth was inhibited by tamoxifen or fulvestrant. MCF-7TAMLT tumor growth was stimulated by tamoxifen) cross-sectional area at week 10 = 0.60 cm2, 95% CI = 0.50 to 0.70 cm2; P<.001) compared with control (0.02 cm2, 95% CI = 0.00 to 0.04 cm2). For MCF-7TAMLT tumors that were initially 0.35 cm2, estradiol-induced regression to 0.18 cm2 (95% CI = 0.15 to 0.21 cm2; P<.001), and tamoxifen or estradiol plus fulvestrant enhanced tumor growth to 1.00 cm2 (95% CI = 0.88 to 1.22 cm2). Estradiol increased the number of apoptotic cells in tumors by
J Clin Endocrinol Metab. 2003 Nov;88(11):5240-7.
Increased risk of falls and increased bone resorption in elderly men with partial androgen deficiency: the MINOS study.
Szulc P, Claustrat B, Marchand F, Delmas PD.
Institut National de la Sante et de la Recherche Medicale, 403 Research Unit, Hopital Edouard Herriot, 69437 Lyon, France.
The goal of this study was to identify the clinical and biological patterns of hypogonadism in a cohort of 1040 elderly men. Residual androgenic activity was estimated by total testosterone as well as the apparent free testosterone concentration (AFTC) and free testosterone index (FTI) calculated on the basis of concentrations of SHBG and total testosterone using appropriate formulae. The lower limit of the normal range defined by 2 SD below the mean in 150 healthy, nonobese, and nonsmoking men, aged 19-40 yr, was calculated for total testosterone (9.26 nmol/liter), AFTC (146 pmol/liter), and FTI (0.14 nmol/nmol). The prevalence of hypogonadism increased with ageing. Hypogonadal men were older and heavier (due to a higher fat body mass) and had lower concentrations of 17 beta-estradiol and androstenedione than men with normal androgenic activity. Men with decreased AFTC had a slightly lower bone mineral density (BMD) at certain sites. Men with decreased FTI had lower appendicular skeletal muscle mass and relative skeletal muscle index. For all three measures of androgenic activity, hypogonadal men had increased levels of the markers of bone resorption. In the multiple regression models including both 17 beta-estradiol and testosterone (total, AFTC, or FTI), 17 beta-estradiol was the only significant determinant of BMD. In the multiple regression models including 17 beta-estradiol and AFTC or FTI, only testosterone was a significant determinant of the variability in bone formation markers, whereas both 17 beta-estradiol and testosterone were significant determinants of the variability of the markers of bone resorption. Hypogonadism was associated with an increase in the
J Cell Physiol. 2004 Feb;198(2):269-76.
17beta-estradiol downregulates beta3-integrin expression in differentiating and mature human osteoclasts.
Saintier D, Burde MA, Rey JM, Maudelonde T, de Vernejoul MC, Cohen-Solal ME.
Inserm U349, Hopital Lariboisiere, Paris, France.
The increased bone resorption observed after estrogen withdrawal is responsible for bone loss and may lead to osteoporosis. The mechanism by which estradiol inhibits bone resorption is known to involve decreased osteoclastogenesis, however, the effect on osteoclast adhesion remains unclear. We examined the in vitro effect of estradiol and raloxifene on human osteoclast differentiation and function. Human peripheral blood mononuclear cells were cultured with M-CSF/RANK-L for 18 days, and we evaluated bone resorption, the expression of the protein and mRNA of the integrins, c-jun and c-fos in the presence or absence of estradiol. In this human model, beta3-integrin expression increased at the mRNA and protein levels during osteoclast differentiation, whereas that of beta5-integrin did not. We found that estradiol and raloxifene directly inhibited bone resorption on bone slices by 50%, and decreased the expression of beta3-integrin mRNA (60%) and protein (20%) in a time-dependent manner. Moreover, the mRNAs of c-fos and c-jun were both diminished by estradiol and raloxifene, particularly in early osteoclasts, but also to a lesser extent in mature cells. These findings suggest that the direct inhibitory action of estradiol on bone resorption may affect human osteoclast differentiation through downregulation of c-fos and c-jun and adhesion through modulation of beta3-integrin. Copyright 2003 Wiley-Liss, Inc.
Endocrinology. 2004 Feb;145(2):706-15. Epub 2003 Nov 06.
Involvement of protein kinase C-dependent mitogen-activated protein kinase p44/42 signaling pathway for cross-talk between estradiol and transforming growth factor-beta3 in increasing basic fibroblast growth factor in folliculostellate cells.
Chaturvedi K, Sarkar DK.
Endocrinology Program, Biomedical Division of the Center of Alcohol Studies and Department of Animal Sciences, Rutgers, The State University of New Jersey, 84 Lipman Drive, New Brunswick, NJ 08901, USA.
We have recently shown that TGF-beta3, in the presence of estradiol, increases the release of basic fibroblast growth factor (bFGF) from folliculostellate (FS) cells in the pituitary. We determined the interactive effects of TGF-beta3 and estradiol on bFGF production and release from FS cells, and the role of the MAPK pathway in TGF-beta3 and estradiol interaction. We found that TGF-beta3 and estradiol alone moderately increased cell content and release of bFGF from FS cells; but together, they markedly increased the peptide. Estradiol and TGF-beta3 alone moderately activated MAPK p44/42; together they produced marked activation of MAPK p44/42. Pretreatment of FS cells with an MAPK kinase 1/2 inhibitor or with protein kinase C inhibitors suppressed the activation of MAPK p44/42, bFGF release, and protein level increases, all of which were induced by TGF-beta3 and estradiol. Estradiol and TGF-beta3, either alone or in combination, increased the levels of active Ras. Furthermore, bFGF induction by TGF-beta3 and estradiol was blocked by overexpression of Ras N17, a dominant negative mutant of Ras p21. Estrogen receptor blocker ICI 182,780 failed to prevent estrogen's and TGF-beta3's effects on bFGF. These data suggest that an estradiol receptor-independent protein kinase C- activated Ras-dependent MAPK pathway is involved in the cross-talk between TGF-beta3 and estradiol to increase bFGF production and/or release from FS cells.
Arch Gynecol Obstet. 2003 Nov;269(1):16-24. Epub 2003 Mar 14.
Immunohistochemical reactivity of myometrial oxytocin receptor in extracorporeally perfused nonpregnant human uteri.
Richter ON, Tschubel K, Schmolling J, Kupka M, Ulrich U, Wardelmann E.
Department of Obstetrics and Gynecology, University of Bonn Medical School, Sigmund-Freud-Strasse 25, 53105 Bonn, Germany. Dr.OliverRichte-online.de
INTRODUCTION. In the pregnant uterus oxytocin and the oxytocin receptor play a major part for uterine contractility and the induction of labor. Clinical evidence implicates that with regard to contractility associated disorders like for example dysmenorrhea also in the nonpregnant and very early pregnant myometrium oxytocin and the oxytocin receptor seem to be more important than believed at the moment. However, little is known about the mutual dependence of the oxytocin receptor, oxytocin and 17-beta-estradiol in the nonpregnant myometrium and about the distribution of the oxytocin receptor in the nonpregnant uterus. Therefore, in the present study we investigated in the nonpregnant myometrium if oxytocin receptor expression can be affected by 17-beta-estradiol and oxytocin stimulation. METHODS. We used a previously established experimental perfusion system for the human uterus. We perfused 10 uteri for 27 h under physiological conditions without 17-beta-estradiol (group A, n=5) or with high 17-beta-estradiol stimulation (group B, n=5) followed by oxytocin stimulation in both groups in the last 3 h of the experiment. The expression of the myometrial oxytocin receptor in both groups was compared immunohistochemically. RESULTS. In comparison to the negative controls the immunohistochemical reactivity demonstrated increasing oxytocin receptor concentrations with maximum levels under 17-beta-estradiol and oxytocin stimulation in the uterine fundus (40% of positive stained cells, p<0.01). However, oxytocin receptor levels did not reach concentrations comparable to specimen of third trimester of pregnancy, which were us
J Nutr. 2003 Nov;133(11):3584-7.
A natural antioxidant mixture from spinach does not have estrogenic or antiestrogenic activity in immature CD-1 mice.
Lomnitski L, Padilla-Banks E, Jefferson WN, Nyska A, Grossman S, Newbold RR.
Life Science Faculty, Bar-Ilan University, Ramat-Gan, Israel.
The use of natural antioxidants and flavonoids in nutritional and pharmaceutical applications is increasing. Because some phytochemicals such as genistein, found in soy products, have estrogenic activity, we investigated the estrogenic potential of a natural antioxidant mixture (NAO) isolated from spinach leaves, using an in vivo uterotrophic bioassay and an in vitro transcriptional activation assay for the estrogen receptor (ER). Outbred female CD-1 mice (17 d old) were given subcutaneous injections of 17beta-estradiol or genistein [500 and 500,000 microg /(kg x d), respectively] as positive controls or NAO [1000 to 1,000,000 microg/(kg x d)] for 3 d. Uterine wet weight/body weight ratios were determined. Both 17beta-estradiol and genistein significantly increased uterine wet weight ratios compared with untreated controls, but NAO did not. Histological examination of the uterus showed that 17beta-estradiol and genistein increased epithelial cell height, number and gland development, but NAO did not. Estrogenic activity of NAO was investigated in vitro using the ER transcriptional activation assay. BG1Luc4E2 cells expressing ER were stably transfected with a luciferase reporter gene responsive to estrogens. 17beta-estradiol dose dependently increased luciferase activity; NAO had no effect. When NAO was tested for antiestrogenic activity, it did not lessen the effects of 17beta-estradiol. These data suggest that NAO does not have estrogenic or antiestrogenic activity. Thus, an antioxidant mixture has been identified that does not have potentially adverse estrogenic activity.
Contemp Top Lab Anim Sci. 2003 Nov;42(6):33-5.
Safe and effective method for chronic 17beta-estradiol administration to mice.
Levin-Allerhand JA, Sokol K, Smith JD.
Rockefeller University, 1230 York Avenue, New York, New York 10021, USA.
Supraphysiological 17beta-estradiol treatment administered via subcutaneous pellets is commonly used in mice. However, despite its efficacy in eliciting a uterotrophic response, we demonstrate that this regimen also was associated with urine retention, hydronephrosis, and ultimately premature death. To determine a safer yet still effective method to chronically treat mice with 17beta-estradiol, we initiated a placebo-controlled study to treat ovariectomized C57BL/6J mice for 6 weeks with various doses of 17beta-estradiol administered either in their drinking water (0.3 to 1000 nM) or via pellets (0.72 mg or 1.7 mg). Uterine weights demonstrated a dose-dependent effect of 17beta-estradiol administered either orally or via pellets; however, the pellet treatments resulted in urine retention. Treatment with either 200 or 1000 nM 17beta-estradiol in the drinking water yielded physiological and supraphysiological uterotrophic responses, respectively, without urine retention, providing safe, effective, and economical ways to treat mice chronically with 17beta-estradiol.
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