A number of changes in anterior pituitary corticotrophs occur after chronic footshock. These include increased ACTH and β-endorphin content and a loss of glucocorticoid negative feedback on corticotropin-releasing hormone (CRH)-stimulated ACTH and β-endorphin secretion, without changes in sensitivity to ovine CRH examined in vitro [9]. The present studies were undertaken to determine whether the in vitro changes were reflected by similar changes in vivo. We developed a fast feedback paradigm using a 5-min swim stress as challenge, with injection of saline or corticosterone immediately prior to swim. Corticosterone reliably decreased ACTH and β-endorphin responses to swim over the 30-min period studied. This feedback inhibition did not occur in rats that were either exposed to 30 min of chronic footshock for 7 or 14 days or in rats that were treated with corticosterone daily for 14 days in a regimen that has been reported to decrease hippocampal glucocorticoid receptors. By contrast, in rats exposed to the less intense stimulus of 30 min swim for 14 days, the fast feedback action of corticosterone was intact. These results suggest that both fast and delayed feedback corticosterone-inhibitory mechanisms may be blocked by relatively high levels of chronic stress or by chronic treatment with corticosterone, possibly as a consequence of decreased hippocampal glucocorticoid receptor number.

This content is only available via PDF.
Copyright / Drug Dosage / Disclaimer
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.
You do not currently have access to this content.