Multiple Unit Activity in the Brain Correlated with Induction and Maintenance of Pseudopregnancy in Rats

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Abstract

Changes in electrical activity of the brain were studied in 34 Wistar female mature rats (including 3 rats with retrochiasmatic section), following electrical stimulation of the uterine cervix on the day of estrus to induce pseudopregnancy. The macro-micro electrodes were chronically implanted into the various areas of the brain and the multiple unit activity (MUA) was recorded with no behavioral restraint. The results are summarized as follows: For several hours after the cervical stimulation (CS), the MUA in the arcuate nucleus (ARC) decreased, whereas that in the anterior hypothalamic area (AHA) and dorsomedial hypothalamic nucleus (DMH) increased. In contrast, from the 1st day until at least the 4th day, the MUA in the ARC increased, except in the frontal section 6.6 of Albe-Fessard’s atlas, while the MUA in the AHA and medial preoptic area (MPO) decreased. The MUA in the ventromedial hypothalamic nucleus (VMH) decreased immediately following or at least 2 days after the CS. From the 4th day of pseudopregnancy, the DMH, AHA, and hippocampus (HPC) showed a decrease in their MUA. CS failed to establish pseudopregnancy in rats with retrochiasmatic section. In such rats, the MUA in the ARC and AMYG showed almost no change, except for a slight and transient decrease immediately after the stimulation. The bursts of MUA characteristic of cyclic rats were not observed in the pseudo-pregnant rats; when the CS failed to induce pseudopregnancy, the characteristic bursts of MUA were suppressed for about 4 days. Afferent impulses caused by the CS may be conducted to the hypothalamic areas through anterior rather than posterior connections. The MUA changes observed for 3 or 4 days after stimulation seem to represent the brain activity that participates in the establishment of pseudopregnancy. Hormones related to the maintenance of pseudopregnancy, such as prolactin, progesterone, estrogen, and others, may cause the MUA changes on the 4th day of pseudopregnancy and, thereafter, by their feedback action.

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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: 1972

Publication date (Print): 1972

Publication date (Electronic): 19 March 2008

Volume: 9

Issue: 1

Pages: 2-19

Affiliations

Second Department of Physiology, Yokohama City University School of Medicine, Yokohama

Article

Publisher ID: 122033 Other ID: Neuroendocrinology 1972;9:2–19

DOI: 10.1159/000122033

PubMed ID: 5008123

SO-VID: 67cdd9ad-0242-437c-915c-0d516da21fc2

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 : 03 December 1970

Date accepted : 12 April 1971

Page count

Pages: 18

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