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      Pineal Rhythm in N-Acetyltransferase Activity in Rats under Different Artificial Photoperiods and in Natural Daylight in the Course of a Year

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      ,
      Neuroendocrinology
      S. Karger AG
      Pineal, N-acetyltransferase, Rhythm, Photoperiod

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          Abstract

          The rhythm in melatonin formation was studied in rats kept in natural daylight throughout the year and in rats housed under different artificial photoperiods. N-acetyltransferase activity was chosen as the indicator of melatonin formation. The period of the high night N-acetyltransferase was shortest in rats kept under LD 16:8 and longest in rats under LD 8:16. A short, 1-day adaptation to longer days, from LD 12:12 to LD 16:8, involved the induction of the morning decline in N-acetyltransferase by an earlier ‘light on’. Following long-term adaptation to LD 16:8, N-acetyltransferase declined spontaneously 1 h before the morning ‘light on’. A short, 1-day adaptation to shorter days, from LD 12:12 to LD 8:16, involved an earlier evening rise in N-acetyltransferase and a spontaneous morning decline at approximately the same time as in LD 12:12. Following long-term adaptation to LD 8:16, the period of high N-acetyltransferase shifted towards the later part of the night and the activity declined 2 h before the ‘light on’. In natural daylight, the period of the high night N-acetyltransferase was shortest in June and longest in December. The morning decline in N-acetyltransferase was probably induced by dawn on April 19 and June 20, but was spontaneous on December 19. The existence of differences in the N-acetyltransferase rhythm and consequently in the rhythm of melatonin formation in natural daylight throughout the year and under different artificial photoperiods supports the hypothesis that the changing rhythmic pattern of melatonin release might be a mechanism by means of which a photic information is transformed into a humoral one.

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          Author and article information

          Journal
          NEN
          Neuroendocrinology
          10.1159/issn.0028-3835
          Neuroendocrinology
          S. Karger AG
          0028-3835
          1423-0194
          1980
          1980
          26 March 2008
          : 31
          : 5
          : 321-326
          Affiliations
          Institute of Physiology, Czechoslovak Academy of Sciences, Prague
          Article
          123095 Neuroendocrinology 1980;31:321–326
          10.1159/000123095
          7442935
          7b1bdbb2-dd1f-45e6-b40b-87b0385e3b83
          © 1980 S. Karger AG, Basel

          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
          : 04 March 1980
          : 23 April 1980
          Page count
          Pages: 6
          Categories
          Original Paper

          Endocrinology & Diabetes,Neurology,Nutrition & Dietetics,Sexual medicine,Internal medicine,Pharmacology & Pharmaceutical medicine
          Rhythm,N-acetyltransferase,Pineal,Photoperiod

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