Growth Hormone-Releasing Hormone and Growth Hormone Secretagogues
Restricted Presence of the Growth Hormone-Releasing Hormone Receptor to Somatotropes in Rat and Human PituitariesMorel G.a · Gallego R.b · Boulanger L.c · Pintos E.b · Garcia-Caballero T.b · Gaudreau P.c
aCNRS UMR 5578, Université Lyon-I, Villeurbanne, France; bDepartment of Morphological Sciences, School of Medicine, University of Santiago, Santiago de Compostela, Spain; cLaboratory of Neuroendocrinology of Aging, Notre-Dame Hospital Research Center, and Department of Medicine, University of Montreal, Canada
Do you have an account?
- Rent for 48h to view
- Buy Cloud Access for unlimited viewing via different devices
- Synchronizing in the ReadCube Cloud
- Printing and saving restrictions apply
Rental: USD 8.50
Cloud: USD 20.00
Specific binding of growth hormone-releasing hormone (GHRH) to its plasma membrane receptor represents the first step of cellular signals leading to exocytotic GH secretion in the anterior pituitary. The GHRH receptor (GHRH-R) has been cloned and belongs to the secretin/glucagon/vasoactive intestinal peptide subfamilly of G-protein-coupled receptors. To study its characteristics in rat and human pituitaries and examine its cellular and subcellular localization, a site-directed polyclonal antibody recognizing the C-terminal portion 392–404 of the rat and human GHRH-R was used. Immunohistochemistry was performed on paraffin-embedded pituitary sections while ultrastructural immunocytology was done on frozen and Lowicryl-resin-embedded ultrathin sections. GHRH-R-like immunoreactivity was restricted to somatotropes and colocalized with GH in both rat and human tissues. No signal was detected in gonadotropes, lactotropes, corticotropes and thyrotropes. At the subcellular level, gold particles were associated with the plasma membrane (observed on ultrathin frozen sections), secretory granule membrane, cytoplasmic matrix, nuclear membrane and nuclear matrix. In the nucleus, gold particles were mainly observed at the junction between eu- and heterochromatin. The highest density of labeling was observed in the cytoplasm (55 vs. 45% in the nucleus), mainly in secretory granules (59% of cytoplasmic labeling) and the plasma membrane. These results support the hypothesis that GHRH-mediated actions in the pituitary are specific to somatotropes and that GHRH-R isoforms and/or ligand-receptor complexes are involved in intracellular trafficking, recycling processes and nuclear functions.
Article / Publication Details
Copyright / Drug Dosage / DisclaimerCopyright: 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 or, in the case of photocopying, direct payment of a specified fee to the Copyright Clearance Center.
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.