Colocalization of Peptide Histidine Isoleucine Amine and Corticotropin-Releasing Factor Immunoreactivity in Neurons of the Rat Hypothalamus: A Surprising Artefact

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Abstract

Indirect immunocytochemistry of corticotropin-releasing factor (CRF) and peptide histidine isoleucine amide (PHI) was performed by the use of antibodies raised to CRF and PHI. The staining intensity was quantitated by using an automated microfluorimeter. CRF and PHI immunoreactive fibres showed a similar pattern of distribution in the zona externa of the median eminence of the rat hypothalamus. Administration of colchicine (50 µg i.c.v.) resulted in the appearance of PHI and CRF immunoreactive cell bodies in the parvocellular part of the paraventricular nucleus. The PHI immunoreactive cell bodies were of low intensity and less abundant than those stained with the CRF antisera. Microfluorimetric measurements of the immunostaining in the median eminence showed parallel changes of PHI and CRF immunostaining after adrenalectomy, administration of reserpine and/or pargyline. In order to evaluate whether these data demonstrate that PHI and CRF are colocalized in hypothalamic neurons, we studied the specificity of PHI immunostaining by the use of a nonbiological gelatin model. Although CRF and PHI do not show structural homologies, the PHI antisera caused staining of PHI containing gels (range: 0.001–1 µ M) but also of rat CRF (rCRF)-containing gels (range: 10–300 µ M). In addition, preincubation of one of the PHI antisera with PHI or rCRF both caused a concentration-dependent quenching of the immunostaining in PHI- and CRF-containing gels and in preparations of the median eminence. Again, higher concentrations of rCRF (100 µ M) than PHI (0.1 µ M) were needed to show immunoinhibition, suggesting that the PHI antiserum has much lower avidity for native and fixed rCRF than for native and fixed PHI. We conclude that PHI immunostaining in the rat median eminence as found under the conditions used, is due, at least partially, to cross-reaction of the PHI antisera with rCRF.

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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: 3

Pages: 338-346

Affiliations

^aDepartment of Pharmacology, Medical Faculty, Free University, Amsterdam, The Netherlands; ^bDepartment of Chemical Pathology, St. Bartholomew’s Centre of Clinical Research, London, UK

Article

Publisher ID: 124666 Other ID: Neuroendocrinology 1986;44:338–346

DOI: 10.1159/000124666

PubMed ID: 3543717

SO-VID: d5263cbd-36c8-43bc-9274-31c47f5b98c0

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 January 1986

Date accepted : 11 June 1986

Page count

Pages: 9

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