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      Neurotoxic Lesions Induced by Monosodium Glutamate Result in Increased Adenopituitary Proopiomelanocortin Gene Expression and Decreased Corticosterone Clearance in Rats

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          Abstract

          Hypothalamic-pituitary-adrenocortical function in rats with brain lesions induced by neonatal monosodium glutamate (MSG) treatment (4 mg/g, 5 administrations, i.p.) was evaluated in the present study. Using in situ hybridization we found increased proopiomelanocortin (POMC) mRNA levels in the adenopituitary and normal corticotropin-releasing hormone mRNA levels in the hypothalamic paraventricular nucleus in MSG-treated rats. The total content of pituitary adrenocorticotropin (ACTH) was not changed, while pituitary ACTH concentration was higher in MSG-treated compared to control rats. The number of ACTH-immunostained cells per a constant area of adenohypophysial section, as measured by immunohistochemistry, was unchanged indicating that no significant condensation of corticotropes occurred. Basal plasma ACTH concentrations were not different, whereas morning corticosterone levels were elevated in rats with MSG treatment. While ACTH response to stress stimuli was similar in both groups of rats, corticosterone response to exogenous ACTH (500 ng/kg, i.v., Synacthen), short-lasting handling and immobilization was of the same magnitude but prolonged in MSG-treated rats. Based on the decline of [<sup>3</sup>H]corticosterone in plasma, a decreased corticosterone clearance rate was found in MSG-treated rats. These findings suggest that MSG treatment results in increased POMC gene expression per corticotrope of the atrophic pituitary resulting in maintenance of normal pituitary ACTH stores and plasma ACTH levels. Elevated basal levels of corticosterone in plasma as well as prolonged corticosterone responses to stimulations in rats treated with MSG seem to be due to a decreased clearance rate of corticosterone.

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          Most cited references 2

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          Ontogeny of circadian corticosterone rhythm in rats treated with monosodium glutamate neonatally

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            Neurotoxin effects on oxytocin, vasopressin and somatostatin in discrete rat brain areas

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              Author and article information

              Journal
              NEN
              Neuroendocrinology
              10.1159/issn.0028-3835
              Neuroendocrinology
              S. Karger AG
              0028-3835
              1423-0194
              1998
              June 1998
              19 June 1998
              : 67
              : 6
              : 412-420
              Affiliations
              Institute of Experimental Endocrinology, Slovak Academy of Sciences, Bratislava, Slovakia
              Article
              54340 Neuroendocrinology 1998;67:412–420
              10.1159/000054340
              9662721
              © 1998 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: 9
              Categories
              Corticotropin and Pro-Opiomelanocortin

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