Decreased Stimulation of Adenylate Cyclase by Growth Hormone-Releasing Factor in the Anterior Pituitary of Old Rats

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Abstract

Adenylate cyclase activity was studied in anterior pituitary homogenates from young adult (6 months) and old (20 and 24 months) male rats. Basal, NaF-, GTP-, 5’-guanylimidodiphosphate (Gpp(NH)p)- and forskolin-stimulated activities were similar in the three groups, implying that the stimulatory guanyl nucleotide regulatory binding site (NS) and the catalytical unit were unaffected by aging. Vasoactive intestinal peptide (VΙP)-stimulated adenylate cyclase activity was also identical in the three groups. The efficacy (i.e., the maximum effect) of growth hormone-releasing factor [GRF(1-29)-NH<sub>2</sub>] on adenylate activity was reduced by 45–49% in old and senescent rats with no change in peptide potency (i.e., the concentration required for half-maximal enzyme stimulation). These results suggest that aging induced a selective loss of functional GRF receptors but influenced neither the coupling between receptors, NS and the catalytic unit nor the efficacy of the catalytic unit per se.

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Author and article information

Journal

Journal ID (publisher-id): NEN

Journal ID (nlm-ta): Neuroendocrinology

Journal ID (doi): 10.1159/issn.0028-3835

Title: Neuroendocrinology

Publisher: S. Karger AG

ISSN (Print): 0028-3835

ISSN (Electronic): 1423-0194

Publication date Subscription-year: 1986

Publication date (Print): 1986

Publication date (Electronic): 01 April 2008

Volume: 44

Issue: 4

Pages: 429-432

Affiliations

^aDepartment of Biochemistry and Nutrition, Medical School, Université Libre de Bruxelles, Brussels; ^bUCB Research Laboratories, Braine l’Alleud, Belgium

Article

Publisher ID: 124682 Other ID: Neuroendocrinology 1986;44:429–432

DOI: 10.1159/000124682

PubMed ID: 3102990

SO-VID: 978ca46b-c0ea-4876-86ca-8ad80fd6b0f1

License:

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.

History

Date received : 30 December 1985

Date accepted : 03 July 1986

Page count

Pages: 4

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