To determine the pineal gland content of melatonin during rat development and the onset of the circadian rhythm, a biochemical and ultrastructural experimental model was designed. Body and pineal gland weights and DNA and protein contents of the pineal glands increased rapidly during ontogenic development. No significant differences in the values of these parameters were observed when the data were obtained during the day or at night. Pineal melatonin content as expressed by pineal gland or by µg of DNA, was very small in 21-day-old fetuses and 5- and 10-day-old suckling rats and the values determined were similar for both day and night. However, in 20-day-old suckling and adult rats higher melatonin concentrations and significant differences between the values obtained during the day and at night were observed. The onset of the circadian melatonin rhythm coincided with the time at which the components involved in melatonin synthesis reached adult levels and pinealocytes adopted an adult morphological appearance as observed with the electron microscope. These results indicate that the appearance of a circadian melatonin rhythm in the rat pineal gland is delayed until the end of the suckling period, although the transfer of melatonin from the mother to the pups may be important for postnatal reproductive and somatic development.

Keywords:
Rat, Ontogeny, Melatonin rhythm, Pineal gland
This content is only available via PDF.
© 1989 S. Karger AG, Basel
1989
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.