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      24-Hour Changes in Catecholamine Synthesis in Rat and Hamster Pineal Glands

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          Abstract

          The purpose of this study was to examine the 24-hour variation in endogenous tyrosine hydroxylase (TH) activity and thus catecholamine (CA) synthesis in the hamster and rat pineal gland. To determine CA synthesis a time course of the accumulation of dihydroxyphenylalanine (DOPA) after DOPA decarboxylase inhibition with m-hydroxybenzylhydrazine (NSD-1015) was measured at 0, 15 and 30 min by liquid chromatography with electrochemical detection. Animals were under long photoperiods (LD 14:10; lights on at 06.00 h). In the hamster pineal gland, CA synthesis was greater in the dark (24.00 h) (0.017 ng/pineal/min) than in the light (12.00 h) (0.008 ng/pineal/min). Similarly, CA synthesis in the rat pineal was 0.037 ng/pineal/min (dark) and 0.005 ng/pineal/min (light). In a 24-hour study, animals were injected with NSD-1015,30 min prior to killing to determine if 24-hour changes were present in CA synthesis. In the hamster, DOPA in the dark (p < 0.001) was significantly greater than in the light (1.33 ± 0.42 ng/pineal at 06.00 h; 0.33 ± 0.07 at 13.00 h) in this study. No significant difference was measured in norepinephrine (NE) concentration during this 24-hour period. In the rat, DOPA accumulation was significantly different (p < 0.001) in the dark as compared to the light (0.86 ± 0.09 ng/pineal at 03.00 h; 0.21 ± 0.08 at 12.30 h). Within this 24-hour period, NE concentration fluctuated significantly between 2.28 ± 0.33 ng/pineal (15.30 h) to 4.65 ± 0.59 (05.30 h). These results indicate for the first time a definite 24-hour rhythm in endogenous TH activity and NE synthesis in the hamster pineal gland even though NE content does not change. In addition, a 24-hour change in CA synthesis and content is present in the rat pineal gland.

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          Author and article information

          Journal
          NEN
          Neuroendocrinology
          10.1159/issn.0028-3835
          Neuroendocrinology
          S. Karger AG
          0028-3835
          1423-0194
          1984
          1984
          28 March 2008
          : 38
          : 3
          : 193-198
          Affiliations
          Department of Anatomy, University of Texas Health Science Center at San Antonio, Tex., USA
          Article
          123890 Neuroendocrinology 1984;38:193–198
          10.1159/000123890
          6144062
          © 1984 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.

          Page count
          Pages: 6
          Categories
          Original Paper

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