Natural and Melatonin-Stimulated Changes in the Circadian Rhythm of Prolactin Secretion in the Ewe during Seasonal Anestrus

There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

Abstract

The relations between the circadian rhythms of melatonin and prolactin, and the effect of melatonin infused into the third ventricle or the mediobasal hypo-thalamus (MBH) on prolactin secretion and dopamine (DA) release were studied in anestrous ewes under increasing daylength conditions. The decreased amplitude and duration of nocturnal melatonin secretion were accompanied with changes in the daily pattern of prolactin secretion. Marked peaks of prolactin occurred after sunrise and melatonin decreases in February, as well as significant evening or nocturnal peaks under long day conditions between April and July. Melatonin infused into the third ventricle evoked an abrupt increase in the concentration of prolactin after 30 min, and the enhanced prolactin level was significantly higher than during the control infusion (range from 204 ± 75 to 248 ± 48 ng/ml vs. 128 ± 68 to 149 ± 93 ng/ml, mean ± SD). The concentrations of DA in MBH perfusates decreased during perfusion of melatonin but to a degree similar to that noted in untreated ewes. These data suggest that short-term infusions of melatonin stimulate the secretion of prolactin in the ewe under increasing daylength conditions, and that this effect is not mediated by changes in DA release.

Related collections

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: 1997

Publication date (Print): 1997

Publication date (Electronic): 09 April 2008

Volume: 66

Issue: 5

Pages: 360-367

Affiliations

The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Science, Jabłonna, Poland

Article

Publisher ID: 127259 Other ID: Neuroendocrinology 1997;66:360–367

DOI: 10.1159/000127259

PubMed ID: 9387855

SO-VID: 0dd66149-24fe-42cc-8731-d27b3bcaad74

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 : 24 December 1996

Date accepted : 17 July 1997

Page count

Pages: 8

Comments

Comment on this article

scite_