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      Biosynthesis of Gonadotropin-Releasing Hormone during the Rat Estrous Cycle: A Cellular Analysis

      ,

      Neuroendocrinology

      S. Karger AG

      GnRH, Estrous cycle

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          Abstract

          In an attempt to understand the regulatory events that control the synthesis of gonadotropin-releasing hormone (GnRH) during the estrous cycle of the rat, we undertook a cellular analysis of time of translation of GnRH mRNA into protein. A specific antiserum, Rb 1076, which recognizes both the extended proGnRH as well as the processed form of the decapeptide was used for immunocytochemical staining. A cell was considered to be actively translating the pro-GnRH mRNA if elements of the rough endoplasmic reticulum (RER), including the outer nuclear envelope, were filled with reaction product. A synthetically quiescent cell contained only immunopositive neurosecretory granules. Cycling rats were killed at various times and all GnRH cells scored as being RER positive (+) or negative (–). On the morning of estrus almost all GnRH neurons in 5 out of 6 of the animals studied were synthesizing their unique peptide. The immunostaining in many of the cells at this time was very pale, suggesting a prior depletion. This was the only time point examined where near uniformity among individuals in a group was observed. At all other times considerable heterogeneity was observed among animals within a group. For example, at 17.30 h on the afternoon of proestrus 50% or more of the GnRH neurons were RER+ in half of the animals; the other half had values of 16–45% RER+. Synthetically active and inactive cells were found in close proximity in all animals. No regional differences were observed; all GnRH cell subpopulations from the level of the diagonal band of Broca through the hypothalamus reflected the population as a whole. These results suggest that only after the preovulatory surge of LH are all GnRH neurons synchronized to initiate synthesis of this neuropeptide.

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          Author and article information

          Journal
          NEN
          Neuroendocrinology
          10.1159/issn.0028-3835
          Neuroendocrinology
          S. Karger AG
          0028-3835
          1423-0194
          1994
          1994
          08 April 2008
          : 59
          : 6
          : 545-551
          Affiliations
          Department of Anatomy and Cell Biology, Columbia University, New York, N.Y., USA
          Article
          126704 Neuroendocrinology 1994;59:545–551
          10.1159/000126704
          8084378
          © 1994 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: 7
          Categories
          Sex Steroids and Regulation of Gonadotropins

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