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      Pituitary-Gonadal Interactions in Perinatal Rats: Relationships of Plasma Luteinizing Hormone and Testosterone Concentrations, and Pituitary Levels of LH Subunit mRNAs

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          Abstract

          The functional state of the pituitary-gonadal axis was studied in rats on days 18.5–21.5 of fetal life (f) and on day 4 postpartum by measurements of plasma levels of luteinizing hormone (LH) and testosterone (T). LH was measured using an ultrasensitive immunofiuorometric assay. In addition, male fetuses were castrated and exposed to the antiandrogen flutamide (FL; 100mg/kg BW) or the Leydig cell-specific cytotoxic agent ethylene dimethane sulphonate (EDS, 50 mg/kg BW on 2 days) by injections of the drugs to the mothers. Besides LH and T, pituitary levels of LH subunit mRNAs were measured in these animals. The results allowed the following conclusions: (1) the plasma LH levels in both sexes are low (<0.05 µg/1, NIH rLH RP-2) on days f18.5 and fl9.5; (2) a 4- to 5-fold increase in plasma LH occurs between days f19.5 and f20.5, and a 3- to 4-fold sex difference appears (females > males); (3) the activation of fetal testicular T production before day f19.5 takes place in the face of very low plasma LH (<0.02 µg/1), suggesting that some factor(s) other than LH may stimulate the testis at this age; (4) the reciprocal changes of plasma LH and T, and the experiments with castration, EDS and FL demonstrate that testicular feedback regulation of LH secretion is functional from day f19.5 onwards; (5) the parallel changes of T in male and female fetal plasma suggest that T in female fetuses comes from male littermates, and (6) the fetal pituitary-testicular axis is less sensitive to hormonal manipulations than that of the postnatal animal, possibly due to interference of maternal and placental hormones with the pituitary-testicular interactions.

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          Author and article information

          Journal
          NEN
          Neuroendocrinology
          10.1159/issn.0028-3835
          Neuroendocrinology
          S. Karger AG
          0028-3835
          1423-0194
          1994
          1994
          09 April 2008
          : 60
          : 1
          : 42-49
          Affiliations
          aDepartment of Physiology, University of Turku, Finland; bInstitute of Developmental Biology, Russian Academy of Sciences, Moscow, Russia
          Article
          126718 Neuroendocrinology 1994;60:42–49
          10.1159/000126718
          8090281
          © 1994 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: 8
          Categories
          Gonadotropic Regulation

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