Reduced Availability of Milk after Central Injections of Corticotropin-Releasing Hormone in Lactating Rats

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Abstract

Corticotropin-releasing hormone (CRH) plays a major role in activating the pituitary-adrenal axis in stress; its central application may therefore be expected to mimic stress. Since stress reportedly disrupts lactation, experiments were designed to study the effects of CRH administration upon the transfer of milk from rat mothers to their pups and to examine some of the possible underlying physiological mechanisms. CRH was administered intracerebroventricularly to primiparous rats on the 8th day of lactation immediately prior to being reunited with 8 of their overnight-separated pups. Changes in litter weights were measured for a period of up to 4 h as an index of milk procurement by the young (milk transfer); a qualitative assessment of maternal behaviour was also made. Treatment of dams with 0.1–1 nmol CRH resulted in a dose-dependent reduction in the amount of milk obtained by the pups. Conscious mothers treated with CRH initially showed intense behavioural activation; these events (mainly hyperlocomotion and grooming) in the mother resulted in reduced opportunities for nipple attachment by the pups and, thus, milk transfer. On the other hand, milk transfer was also significantly reduced in urethane-anaesthetized mothers treated with CRH, indicating that behavioural activation cannot have been the sole factor underlying the CRH-induced inhibition of milk transfer in awake dams. Although oxytocin (OT) release is stimulated by a variety of stressors, the possibility of an inhibitory effect of CRH upon OT secretion and/or disruption of the reflex arc serving milk ejection was considered. The peripheral administration of OT (100 mU/ rat s.c.) did not, however, surmount the inhibitory actions of CRH upon milk transfer. In view of other reports that CRH may in fact enhance OT secretion, it is tentatively proposed that the inability of exogenously administered OT to facilitate milk transfer might be related to the known effects of centrally applied CRH upon the autonomic nervous system.

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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: 1994

Publication date (Print): 1994

Publication date (Electronic): 08 April 2008

Volume: 59

Issue: 1

Pages: 72-77

Affiliations

Departments of ^aNeuropharmacology, ^bNeuroendocrinology and ^cBiostatistics, Max Planck Institute of Psychiatry, and ^dInstitute of Pharmacology, Toxicology and Pharmacy, Ludwig Maximilian University, München, FRG

Article

Publisher ID: 126640 Other ID: Neuroendocrinology 1994;59:72–77

DOI: 10.1159/000126640

PubMed ID: 8145896

SO-VID: 11174229-5a7d-4680-a4c3-f6aa46fc0826

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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 : 12 March 1993

Date accepted : 09 July 1993

Page count

Pages: 6

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