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      Ultrastructural Effects of Estradiol and 3α-Androstane-3α,17β-diol on Neurons within the Ventromedial Nucleus of the Hypothalamus

      ,

      Neuroendocrinology

      S. Karger AG

      Gonadal steroids, Ventromedical nucleus, Chromatin, Endoplasmic reticulum

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          Abstract

          The metabolite of dihydrotestosterone, 5α-androstane-3α,17β-diol (3α-Diol), is a potent inhibitor of estrogen-induced gonadotropin and prolactin secretion and lordosis behavior in the female rat. This study examined whether 3α-Diol can counteract the ultrastructural changes which are known to occur in the ventromedial nucleus (VMN) of the hypothalamus following estrogen treatment. Ovariectomized rats were treated with estradiol (E<sub>2</sub>; n = 7), 3α-Diol (n = 5), E<sub>2</sub> and 3α-Diol (n = 6), or received control (n = 6) treatments. E<sub>2</sub> was administered in subcutaneous capsules for two discontinuous 2-hour periods separated by 5 h, a ‘pulsed’ treatment regimen known to mimic the timing of endogenous E<sub>2</sub> action and to influence neuronal ultrastructure in the VMN. Animals given 3α-Diol received subcutaneous injections (6 mg/kg) 3 h prior to each implantation of E<sub>2</sub> or empty capsules. Control animals received vehicle 3 h prior to implantation of blank capsules. Animals were perfused 24 h after initial hormone treatment and neurons from the ventrolateral portion of the VMN were examined using electron microscopy. Separately, both E<sub>2</sub> and 3α-Diol treatment increased somal and nuclear size, altered somal and nuclear shape, and increased the numbers of lysosomes present in the cytoplasm above control levels. E<sub>2</sub> treatment resulted in increased stacking of the rough endoplasmic reticulum while 3α-Diol treatment resulted in an unusual plexiform rough endoplasmic reticulum distribution. In contrast, combined treatment with E<sub>2</sub> and 3α-Diol resulted in cells which were similar to ovariectomized control cells on these measures. All steroid treatments decreased the amount of heterochromatin present within the nucleus compared to that seen in controls. Thus, 3α-Diol influences the ultrastructural characteristics of neurons within the VMN in a manner somewhat though not altogether similar to E<sub>2</sub>. However, 3α-Diol given in combination with E<sub>2</sub> counteracts or prevents the actions of E<sub>2</sub> within these same neurons.

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          Author and article information

          Journal
          NEN
          Neuroendocrinology
          10.1159/issn.0028-3835
          Neuroendocrinology
          S. Karger AG
          0028-3835
          1423-0194
          1995
          1995
          09 April 2008
          : 61
          : 6
          : 669-679
          Affiliations
          Department of Biology, Boston University, Boston, Mass., USA
          Article
          126894 Neuroendocrinology 1995;61:669–679
          10.1159/000126894
          7659191
          © 1995 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: 11
          Categories
          Gonadotropins and Reproduction

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