+1 Recommend
1 collections
      • Record: found
      • Abstract: found
      • Article: found

      Effect of Repeated Stimulation by Thyrotropin-Releasing Hormone (TRH) on Thyrotropin and Prolactin Secretion in Perfused Euthyroid and Hypothyroid Rat Pituitary Fragments


      Hormone Research in Paediatrics

      S. Karger AG

      Hypothyroid, Pituitary, Thyrotropin, Prolactin, TRH, Perfusion, Euthyroid

      Read this article at

          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.


          The previously reported refractoriness of pituitary response to thyrotropin-releasing hormone (TRH) stimuli was investigated here in an in vitro perfusion system using pituitary tissue from euthyroid and hypothyroid rats. Thyroid-stimulating hormone (TSH) and prolactin (PRL) responses to TRH (28 pmol) were significantly greater in hypothyroid tissue compared with euthyroid. Hypothyroid tissue showed a reduction in response to two consecutive stimuli in both TSH and PRL, however the TSH decline in response was more marked than PRL. Euthyroid tissue showed no significant decline in response to TRH. An increase in the dose of TRH (112 pmol), administered to euthyroid tissue, resulted in increased TSH and PRL response, but no decline in response to sequential stimuli was observed. Three consecutive stimuli by TRH (28 pmol) of hypothyroid tissue resulted in a consistent decline in TSH response. The decline in PRL response only reached statistical significance by the third stimulation. Euthyroid and hypothyroid pituitary tissue was subjected to sequential depolarising stimulation with KCl (50 µmol). Euthyroid tissue showed no decline in response in either TSH or PRL. In hypothyroid tissue only, the decline in TSH response reached statistical significance. This decline in TSH response was significantly smaller than the decline in response observed in hypothyroid tissue stimulated with TRH. Refractoriness of hypothyroid pituitary tissue to repeated TRH stimuli is reported here. Our data suggest that the decline in hormonal response cannot be explained solely on the basis of tissue depletion.

          Related collections

          Author and article information

          Horm Res Paediatr
          Hormone Research in Paediatrics
          S. Karger AG
          26 November 2008
          : 20
          : 4
          : 269-276
          Department of Medicine, University of Birmingham, Queen Elizabeth Hospital, Birmingham, UK
          180007 Horm Res 1984;20:269–276
          © 1984 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: 8


          Comment on this article