J Steroid Biochem Mol Biol. 2003 Jul;86(1):79-92.
Characterisation of estrogenic 17beta-hydroxysteroid dehydrogenase (17beta-HSD) activity in the human brain.
Steckelbroeck S, Watzka M, Reissinger A, Wegener-Toper P, Bidlingmaier F, Bliesener N, Hans VH, Clusmann H, Ludwig M, Siekmann L, Klingmuller D.
Department of Pharmacology, University of Pennsylvania School of Medicine, 130C John Morgan Building, 3620 Hamilton Walk, Philadelphia, PA 19104-6084, USA. st_steckelbroeotmail.com
Estrogens play a crucial role in multiple functions of the brain and the proper balance of inactive estrone and active estradiol-17beta might be very important for their cerebral effects. The interconversion of estrone and estradiol-17beta in target tissues is known to be catalysed by a number of human 17beta-hydroxysteroid dehydrogenase (17beta-HSD) isoforms. The present study shows that enzyme catalysed interconversion of estrone and estradiol-17beta occurs in the human temporal lobe. The oxidative cerebral pathway preferred estradiol-17beta to Delta(5)-androstenediol and testosterone, whereas the reductive pathway preferred dehydroepiandrosterone (DHEA) to Delta(4)-androstenedione and estrone. An allosteric Hill kinetic for NAD-dependent oxidation of estradiol-17beta was observed, whereas a typical Michaelis-Menten kinetic was shown for NADPH-dependent reduction of estrone. Investigations of the interconversion of estrogens in cerebral neocortex (CX) and subcortical white matter (SC) preparations of brain tissue from 12 women and 10 men revealed no sex-differences, but provide striking evidence for the presence of at least one oxidative membrane-associated 17beta-HSD and one cytosolic enzyme that catalyses both the reductive and the oxidative pathway. Membrane-associated oxidation of estradiol-17beta was shown to be significantly higher in CX than in SC (P<0.05), whereas the cytosolic enzyme activities were significantly higher in SC than in CX (P<0.0005). Finally, real-time RT-PCR analyses revealed that besides
J Org Chem. 2003 Sep 5;68(18):7063-70.
Synthesis of 17-alpha-substituted estradiol-pyridin-2-yl hydrazine conjugates as effective ligands for labeling with Alberto's complex fac-[Re(OH2)3(CO)3]+ in water.
Arterburn JB, Corona C, Rao KV, Carlson KE, Katzenellenbogen JA.
Department of Chemistry and Biochemistry MSC 3C, New Mexico State University, P.O. Box 30001, Las Cruces, New Mexico 88003, USA. jarterbmsu.edu
The development of (99m)Tc-estradiol radiopharmaceuticals would be advantageous for the detection of estrogen receptor-positive breast tumors. Estradiol derivatives conjugated to organometallic tricarbonyl-Tc(I) and related Re(I) complexes are capable of achieving high receptor binding affinity, but effective methods for synthesizing radiolabeled complexes in water are not available. Our interest in the synthesis of 2-hydrazinopyridines as ligands for Tc and Re led us to investigate Pd-catalyzed amination reactions of halo-pyridine substrates with di-tert-butyl hydrazodiformate. Both 2- and 4-substituted halo-pyridine substrates undergo C-N coupling with di-tert-butyl hydrazodiformate to produce Boc-protected pyridine hydrazine derivatives. Only highly electrophilic 3-pyridine halides were converted to the hydrazine. The Boc-protected 5-bromopyridin-2-yl hydrazine substrate 3 was prepared by regioselective substitution at the 2-position of 2,5-dibromopyridine. This bifunctional chelate was attached to ethynyl or vinyl groups at the 17alpha position of estradiol, using Sonogashira and Suzuki/Miyaura coupling reactions to synthesize 1 and 2 in high yields, respectively. Deprotection of 1 under acidic conditions provided the hydrazine hydrochloride salt 25. The 17alpha-estradiol-tricarbonylrhenium(I) complex 4 was synthesized by labeling 25 with fac-[Re(OH(2))(3)(CO)(3)](+) in aqueous ethanol. This complex exhibited excellent stability and high receptor binding affinity for the estrogen receptor, and it is a promising model for evaluation of the analogous Tc-99m complexes as diagnost
Mol Cell Neurosci. 2002 Nov;21(3):512-20.
Estrogen-receptor-dependent regulation of neural stem cell proliferation and differentiation.
Brannvall K, Korhonen L, Lindholm D.
Department of Neuroscience, Neurobiology, Uppsala University, Biomedical Center, Husargatan 3, Box 587, S-75123, Uppsala, Sweden.
Estrogen has profound effects on function and plasticity of the nervous system. Receptors for estrogen (ERs) are expressed by neurons in several areas of the brain. Here we demonstrate that embryonic and adult rat neural stem cells (NSC) express ERalpha and ERbeta, 17beta-Estradiol treatment decreased the proliferation of NSC stimulated by epidermal growth factor (EGF), which was due to the upregulation of the cyclin-dependent kinase (CDK) inhibitor, p21(Cip1). The modulatory effect of 17beta-estradiol on EGF was more pronounced in adult NSC. However, 17beta-estradiol alone increased the proliferation of embryonic, but not adult, NSC. The effect of 17beta-estradiol was inhibited by the ER antagonist, ICI-182780, showing an involvement of ERs. 17beta-Estradiol also increased the ratio of neurons to glia cells in embryonic NSC, but not in adult NSC, suggesting an influence on neurogenesis during embryonic development. The data show that estrogen, via ER, affects the proliferation and differentiation of NSC cells, probably acting in conjunction with other factors governing NSC development.
J Neurochem. 2003 Sep;86(6):1498-505.
Estrogens inhibit l-glutamate uptake activity of astrocytes via membrane estrogen receptor alpha.
Sato K, Matsuki N, Ohno Y, Nakazawa K.
Division of Pharmacology, National Institute of Health Sciences, Kamiyoga, Setagaya-ku, Tokyo, Japan. kasatihs.go.jp
We investigated the effects of estrogen-related compounds including xenoestrogens [17beta-estradiol (E2), 17alpha-ethynylestradiol (EE), diethylstilbestrol (DES), p-nonylphenol (PNP), bisphenol A (BPA) and 17alpha-estradiol (17alpha)] on l-glu uptake by cultured astrocytes via glutamate-aspartate transporter (GLAST). After 24 h treatment, E2 inhibited the l-glu uptake at 1 micro m and higher concentrations. EE and DES also inhibited the l-glu uptake at 1 nm and higher concentrations. The other four compounds had no effect. The effects of E2, EE and DES were completely blocked by 10 nm of ICI182 780 (ICI). beta-Estradiol 17-hemisuccinate : bovine serum albumin (E2-BSA), a membrane-impermeable conjugate of E2, also elicited the inhibition of l-glu uptake at 1 nm and higher concentrations, and the effect was blocked by ICI. 16alpha-Iodo-17beta-estradiol (16alphaIE2), an estrogen receptor alpha (ERalpha) selective ligand, revealed an inhibitory effect at 10 nm, while genistein, an ERbeta selective ligand, failed to reveal such an effect at this concentration. Western blot analysis showed that the predominant ER of cultured astrocytes was ERalpha. The colocalization of ERalpha with GLAST on plasma membranes was immunohistochemically detected in these cells. From these results, we concluded that estrogens down-regulate l-glu uptake activity of astrocytes via membrane ERalpha.
Endocrinology. 2003 Oct;144(10):4315-24. Epub 2003 Jul 03.
Short-term activation by low 17beta-estradiol concentrations of the Na+/H+ exchanger in rat aortic smooth muscle cells: physiopathological implications.
Incerpi S, D'Arezzo S, Marino M, Musanti R, Pallottini V, Pascolini A, Trentalance A.
Department of Biology, University of Rome 'Roma Tre,' Viale Marconi, 446, 00146 Roma, Italy. incerpniroma3.it.
Low physiological concentrations of 17beta-estradiol increased the intracellular pH of rat aortic smooth muscle cells by a rapid nongenomic mechanism. This effect was due to stimulation of the Na+/H+ exchanger activity, measured using the intracellular pH-sensitive fluorescent probe 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein. The 17beta-estradiol gave rise to a bell-shaped dose response, with a maximum at 10-12 m and no significant effect at 10-9 m. The specificity of the effect was verified by the use of the Na+/H+ exchanger inhibitor 5-(ethyl-N-isopropyl)amiloride and the lack of effect of the isomer 17alpha-estradiol. Inhibitors of the nuclear estrogen receptors, tamoxifen and ICI 182,780, completely prevented activation of the exchanger by 17beta-estradiol. The effect of low estrogen concentrations on the intracellular pH was mimicked by both norepinephrine and phenylephrine, suggesting a connection between the increase of intracellular pH and the muscle contraction process. The transduction mechanism for this nongenomic effect of estrogens did not involve modulation of the cAMP content, whereas inositol 1,4,5-trisphosphate, protein kinase C and MAPK pathways appear to play a role, as indicated by both pharmacological approaches and immunoblot experiments on protein kinase C translocation and ERK phosphorylation. These results for the first time provide evidence for a nongenomic effect of low physiological concentrations of 17beta-estradiol on intracellular pH that, together with other factors, may contribute to the development of hypertension and atherosclerosis in men and postmenopausal
Endocrinology. 2003 Oct;144(10):4289-97. Epub 2003 Jun 19.
Prepubertal administration of estradiol valerate disrupts cyclicity and leads to cystic ovarian morphology during adult life in the rat: role of sympathetic innervation.
Rosa-E-Silva A, Guimaraes MA, Padmanabhan V, Lara HE.
Department of Physiology, Universidad de Sao Paulo, Brazil.
Administration of estradiol valerate (EV) to adult rats leads to anovulation and cystic ovarian morphology. Sympathetic ovarian nerve denervation (SONX) overcomes this disruption. In this study, we determined whether EV administration to juvenile rats prevents achievement of reproductive competence, disrupts cyclicity, and whether this programming is facilitated via activation of the sympathetic nerve input to the ovary. Prepubertal rats were administered 2 mg EV in corn oil or corn oil alone. One half of the animals from each group underwent SONX on d 71 of life. Rats were euthanized on d 91 for determination of serum gonadotropins, progesterone, Delta4 androstenedione, and estradiol concentrations, ovarian norepinephrine (NE), and 3beta-hydroxysteroid dehydrogenase (3beta-HSD) activities and ovarian dynamics. Results revealed that EV administration during juvenile period advanced pubertal onset, suppressed circulating LH, FSH, and Delta4 androstenedione, increased ovarian NE, estradiol, and 3beta-HSD activities, disrupted ovarian dynamics evidenced as absent corpus luteum and presence of ovarian cysts and culminated in anovulation. SONX restored cyclicity in these animals, normalized LH, estradiol, ovarian 3beta-HSD activities, and ovarian dynamics as evidenced by the disappearance of ovarian cysts and appearance of corpus luteum and restored corpus luteum function. These findings provide evidence that EV exposure during juvenile life leads to long-lasting deleterious reproductive consequences via activation of the sympathetic ovarian nerve.
Endocrinology. 2003 Oct;144(10):4466-77. Epub 2003 Jul 17.
Dendritic growth and spine formation in response to estrogen in the developing Purkinje cell.
Sakamoto H, Mezaki Y, Shikimi H, Ukena K, Tsutsui K.
Laboratory of Brain Science, Faculty of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima 739-8521, Japan.
Neurosteroids are synthesized de novo in the brain, and the cerebellar Purkinje cell is a major site for neurosteroid formation. We have demonstrated that the Purkinje cell possesses intranuclear receptor for progesterone and actively produces progesterone de novo from cholesterol only during rat neonatal life, when cerebellar cortical formation occurs dramatically. We have further demonstrated that progesterone promotes dendritic growth, spinogenesis, and synaptogenesis via its receptor in this neuron in the neonate. On the other hand, estrogen may also play an important role in the process of cerebellar cortical formation, because the neonatal rat Purkinje cell possesses estrogen receptor (ER)beta. However, estrogen formation in the neonatal cerebellum is still unclear. In this study, we therefore analyzed the biosynthesis and action of estrogen in Purkinje cells during neonatal life. RT-PCR-Southern and in situ hybridization analyses showed that Purkinje cells expressed the key enzyme of estrogen formation, cytochrome P450 aromatase, in neonatal rats. A specific enzyme immunoassay for estradiol further indicated that cerebellar estradiol concentrations in the neonate were significantly higher than those in the prepuberty and adult. Both in vitro and in vivo studies with newborn rats showed that estradiol promoted dose-dependent dendritic growth of Purkinje cells. Estradiol also increased the density of Purkinje dendritic spines. These effects were inhibited by the ER antagonist tamoxifen. These results suggest that estradiol in the developing Purkinje cell promotes dendritic growth and spinogenesis via ERbeta in this neuron. Estradiol as well as progesterone may contribute to the
Hepatol Res. 2003 Aug;26(4):348-352.
Regulation of biliary cholesterol secretion is associated with abcg5 and abcg8 expressions in the rats: effects of diosgenin and ethinyl estradiol.
Kamisako T, Ogawa H.
Department of Hygiene, Kinki University School of Medicine, 377-2 Ohnohigashi, Osakasayama, 589-8511, Osaka, Japan
In this study, we evaluate the effect of diosgenin, ethinyl estradiol and these co-administration on changes of lipoprotein metabolism and expression of hepatic genes those are important for cholesterol metabolism including the recently identified abcg5 and abcg8 in male Wistar rats. Rats were subjected to four experimental groups: (1) control group, (2) diosgenin group, which was fed the diet containing 1% diosgenin for 7 days, (3) ethinyl estradiol group, which received ethinyl estradiol in a dose of 5 mg/kg daily for 5 days, (4) diosgenin-ethinyl estradiol group, which received ethinyl estradiol treatment and was fed the diet containing 1% diosgenin. Diosgenin-feeding induced the hepatic abcg5/abcg8 expressions and biliary cholesterol secretion. Ethinyl estradiol administration reduced hepatic abcg5/abcg8 expressions and biliary cholesterol secretion. There was a positive correlation between hepatic expressions of abcg5/abcg8 and biliary cholesterol secretion. These findings strongly suggest that abcg5 and abcg8 are key proteins for biliary cholesterol excretion. Diosgenin-feeding did not affect the hepatic abcg5/abcg8 expressions and biliary cholesterol excretion in ethinyl estradiol-treated rat. Serum bile acid and bilirubin were higher and biliary bile acid and bilirubin secretions were lower in diosgenin-ethinyl estradiol group than those in ethinyl estradiol group. This finding suggests that diosgenin enhances the cholestatic effect of ethinyl estradiol in the rat. In conclusion, alteration of biliary cholesterol secretion is related to the expressions of hepatic abcg5 and abcg8 in diosgenin- or ethinyl estradiol-treated rat.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12963437&dopt=Abstract estradiol [PubMed - as supp
J Cardiovasc Pharmacol. 2003 Jan;41(1):4-13.
Contribution of K+ channels to relaxation induced by 17beta-estradiol but not by progesterone in isolated rat mesenteric artery rings.
Tsang SY, Yao X, Chan HY, Wong CM, Chen ZY, Au CL, Huang Y.
Department of Physiology, Chinese University of Hong Kong, Shatin, Hong Kong, China.
17beta-Estradiol and progesterone were found to relax various vascular beds through multiple mechanisms. However, the exact ionic mechanisms underlying the acute relaxant responses to both hormones are incompletely understood. This study was aimed to examine the possible role of K channel activation in the relaxation induced by both hormones in isolated rat mesenteric artery rings. Isometric tension of each ring was measured with Grass force displacement transducers. In rat endothelium-denuded rings preconstricted by 9,11-dideoxy-11alpha,9alpha-epoxy-methanoprostaglandin F (U46619), the relaxation induced by 17beta-estradiol was partially inhibited by tetrapentylammonium, 4-aminopyridine, iberiotoxin, BaCl, and tertiapin-Q but not by tetraethylammonium, charybdotoxin, apamin, or glibenclamide. In contrast, these putative K channel blockers, except for glibenclamide, did not affect the relaxant response to progesterone. In 4 x 10(-2) K -preconstricted rings, the K channel blockers lost their inhibitory effects on 17beta-estradiol-induced relaxation. Endothelium did not seem to be involved in the effects of K channel blockers on 17beta-estradiol-mediated relaxation. Nifedipine-induced relaxation was not inhibited but was instead enhanced by tetrapentylammonium, iberiotoxin, 4-aminopyridine, and BaCl2. The above results indicate that in rat mesenteric artery rings, nonselective activation of K channels contributes partially to the relaxation induced by 17beta-estradiol. These K channels involved in the estrogen response appeared to be sensitive to inhibition by K(Ca), K, and K(IR) channel blockers. Lack of effect of K channel blockers on progesterone-induced relaxation suggests t
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