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      Involvement of Corticotropin-Releasing Hormone and Endogenous Opioid Peptides in Prolactin-Suppressed Gonadotropin Releasing Hormone Release in vitro

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          Abstract

          Corticotropin-releasing hormone (CRH) has been shown capable of inhibiting hypothalamic gonadotropin-releasing hormone (GnRH) release through activation of an endogenous opioid peptide (EOP)-dependent mechanism. Recently, we have shown that prolactin (PRL) stimulates CRH release and inhibits GnRH release by hypothalami explanted from male rats. Thus, the present study was undertaken to investigate whether the inhibitory effect of PRL on GnRH release in vitro is mediated by CRH and/or EOP. To this aim, the release of GnRH in response to PRL was evaluated in presence of CRH<sub>9–41</sub> α-helical (CRH<sub>9–41</sub>), a CRH receptor antagonist, and/or naloxone (NAL), a nonselective opioid receptor antagonist, using a static hypothalamic organ culture system which enabled us to evaluate immunoreactive GnRH (iGnRH) release from individually incubated longitudinally halved hypothalamic. As previously shown, PRL at the concentration of 100nmol/l inhibited basal iGnRH release by about 35%. CRH<Sub>9–41</Sub> or NAL overcame the inhibitory effect of PRL on iGnRH release in a concentration-dependent fashion. The simultaneous co-incubation with both antagonists was not more effective than each single antagonist. CRH<sub>9–41</sub> did not have any effect on basal iGnRH release whereas NAL, as previously reported, increased it. In addition, PRL at the concentration of 100 nmol/l stimulated basal hypothalamic β-endorphin (β-EP) release. In conclusion, these data show that antagonism to CRH receptors counteracts the suppressive effects of PRL upon GnRH release and that PRL is able to stimulate hypothalamic β-EP release in vitro.

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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
          09 April 2008
          : 60
          : 3
          : 291-296
          Affiliations
          aFirst Internal Medicine Department, University of Catania Medical School, Catania, Italy; bThird Internal Medicine Department, Erasmus University, Rotterdam, The Netherlands; cDivision of Andrology, University of Catania Medical School, Catania, Italy
          Article
          126761 Neuroendocrinology 1994;60:291–296
          10.1159/000126761
          7969787
          © 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: 6
          Categories
          Gonadotropins and Prolactin

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