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      Interaction of Rat Adenohypophyseal Vasopressin Receptors with Vasopressin Analogues Substituted at Positions 7 and 1: Dissimilarity from the V 1 Vasopressin Receptor

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          Abstract

          We readdressed the question of whether or not rat adenohypophyseal vasopressin receptors have a ligand selectivity which is similar to that of the V<sub>1</sub> subtype of vasopressin receptors. Vasopressin analogues substituted in positions 7 and 1 were used. By incubating rat anterior pituitary quarters or by perifusing rat isolated anterior pituitary cells the effect of the vasopressin analogues on the release of β-endorphin-like or adrenocorticotropin-like immunoreactive was examined. The replacement of the proline residue in position 7 by sarcosine or N-methyl-alanine did not change the maximum effect reached but increased the EC50 values 20- or 5-fold, respectively, when compared with arginine vasopres sin. This decrease in β-endorphin-releasing activity was no longer observed after additional removal of the α-amino group of cysteine in position 1. Since these substitutions are known to drastically reduce vasopressor activity, these data sugges that the β-endorphin-releasing activity of vasopressin can be dissociated from its V<sub>1</sub> receptor activity. Vasopressin ana logues substituted in position 7 and with deaminopenicillamine or β-mercapto-ββ-cyclopentamethylenepropionic acid it position 1 were found to be weak antagonists of the β-endorphin-releasing activity of vasopressin. Since these analogue: are potent antagonists at the V<sub>1</sub> receptor, these data suggest that the deaminopenicillamine and, more so, the β-mercapto ββ-cyclopentamethylenepropionic acid residues in position 1 of vasopressin are strong ‘binding elements’ at the V<sub>1</sub> vaso pressin receptor but weak ‘binding elements’ at the adenohypophyseal vasopressin receptor. A positive correlation was found between the EC50 values or inhibition constants of the analogues for their effect on β-endorphin release on the on< hand and their potency to displace <sup>3</sup>H-arginine vasopressin binding to anterior pituitary membranes on the other hand Therefore, these data support and extend previous suggestions that the structural requirements of the adenohypophysea vasopressin receptor differ from those of the V<sub>1</sub> vasopressin receptor. In this sense, the adenohypophyseal vasopressin receptor may represent a novel type of vasopressin receptors.

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          Author and article information

          Journal
          NEN
          Neuroendocrinology
          10.1159/issn.0028-3835
          Neuroendocrinology
          S. Karger AG
          0028-3835
          1423-0194
          1986
          1986
          01 April 2008
          : 44
          : 3
          : 390-396
          Affiliations
          aDepartment of Pharmacology, University of Freiburg i.Br., and bMax-Planck-Institut für Biophysik, Frankfurt am Main, FRG
          Article
          124674 Neuroendocrinology 1986;44:390–396
          10.1159/000124674
          3027602
          © 1986 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
          Original Paper

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