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      Interaction of the Signalling Pathways of Insulin-Like Growth Factor-I and Sex Steroids in the Neuroendocrine Hypothalamus

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          Abstract

          Among the numerous endocrine signals that affect the central nervous system, sex steroids play an important +role. It has been recently postulated that part of the effects of these hormones on the brain may be mediated by trophic factors, such as insulin-like growth factor I (IGF-I). Both estradiol and IGF-I increase the survival and differentiation of developing fetal rat hypothalamic neurons in culture. The effect of estradiol is blocked by the pure estrogen receptor antagonist ICI 182,780, by an antisense oligonucleotide to the estrogen receptor, and by an antisense oligonucleotide to IGF-I. In turn, the effect of IGF-I is blocked by ICI 182,780 and by the antisense oligonucleotide to the estrogen receptor. These findings indicate that estrogen-induced activation of the estrogen receptor in developing hypothalamic neurons requires the presence of IGF-I and that both estradiol and IGF-I use the estrogen receptor to mediate their trophic effects on hypothalamic cells. In vivo, sex steroids affect IGF-I levels in the endocrine hypothalamus. IGF-I levels in tanycytes, a specific subtype of glial cells present in the arcuate nucleus and median eminence, are sexually dimorphic in the rat, increase with the onset of puberty, and are regulated by perinatal and adult levels of sex steroids. These changes may be due to hormonal modifications of IGF-I uptake by tanycytes from blood or cerebrospinal fluid. Therefore, this type of glial cell appears to play a central role in the interaction of sex steroids and IGF-I in the hypothalamus.

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          Author and article information

          Journal
          HRE
          10.1159/issn.0018-5051
          Hormone Research in Paediatrics
          S. Karger AG
          978-3-8055-6432-8
          978-3-318-00112-9
          0018-5051
          2571-6603
          1996
          1996
          09 December 2008
          : 46
          : 4-5
          : 160-164
          Affiliations
          aInstitute Cajal, CSIC, Madrid, Spain; bUniversidad de Guadalajara, Mexico; cUniversidad Autónoma de Madrid, Spain, and dDepartment of Obstetrics and Gynecology, Yale University School of Medicine, New Haven, Conn., USA
          Article
          185016 Horm Res 1996;46:160–164
          10.1159/000185016
          © 1996 S. Karger AG, Basel

          Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher. Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug. Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.

          Page count
          Pages: 5
          Categories
          Session 1: Neuroendocrinology

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