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      Interaction off αT3-1 Cells with Lactotropes and Somatotropes of Normal Pituitary in vitro

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          Abstract

          A pituitary cell population of 14-day-old female rats, containing lactotropes and somatotropes but deprived of gonadotropes, was prepared by unit gravity sedimentation through a serum albumin gradient and allowed to reaggregate either as such or after mixing this population with cells of the gonadotropic αT3-1 cell line. In a perifusion system gonadotropin-releasing hormone (GnRH) had no effect on prolactin (PRL) and growth hormone (GH) release in the former aggregates but stimulated PRL release in the latter. In the αT3-l cell-containing aggregates GnRH showed a biphasic effect on GH release: inhibition during exposure to GnRH followed by a rebound secretion upon removal of the peptide. The aggregation capacity of αT3-l cells with the normal pituitary cells was demonstrated by using an αT3-l cell clone stably transfected with the reporter gene β-galactosidase. Perifusion of the gonado-trope-deprived aggregates with medium conditioned by αT3-1 cell provoked a rapid stimulation of PRL release and a biphasic effect on GH release. Medium conditioned by the cortico-tropic cell line AtT20 also stimulated PRL release but had no concomitant effect on GH release. Medium conditioned by αT3-l cells, when added for 40 h to aggregates of 14-day-old rat pituitary, provoked an increase in the number of <sup>3</sup>H-thymidine (<sup>3</sup>H-T)-labelled lactotropes and a decreased in the number of <sup>3</sup>H-T-labelled somatotropes. The conditioned medium was concentrated on Sep-Pak C18 and ultrafiltrated through an Amicon membrane with 3-kD molecular weight cut-off and the retained molecules separated by reversed-phase HPLC. The material stimulating <sup>3</sup>H-T labelling of lactotropes eluted from the column with a different retention time than material inhibiting <sup>3</sup>H-T labelling of somatotropes, suggesting that the effect on lactotropes is mediated by (a) molecule(s) different from that affecting somatotropes. The effects of αT3-l cells and their secretion products on lactotropes and somatotropes were comparable to those we previously observed using enriched populations of normal gonadotropes. The HPLC elution profiles of the substances affecting <sup>3</sup>H-T incorporation as well as the specificity of these effects were also similar to that of the substances isolated previously from gonadotrope-conditioned medium. The present data, therefore, support previous conclusions on the paracrine control of the lactotrope/somatotrope lineage by the gonadotropes. Further purification and chemical characterization of the growth factors with selective action on lactotropes and somatotropes may lead to a better understanding of the development of the latter lineage.

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          Author and article information

          Journal
          NEN
          Neuroendocrinology
          10.1159/issn.0028-3835
          Neuroendocrinology
          S. Karger AG
          0028-3835
          1423-0194
          1995
          1995
          09 April 2008
          : 61
          : 3
          : 326-336
          Affiliations
          Laboratory of Cell Pharmacology, Department of Molecular Cell Biology, University of Leuven, Belgium
          Article
          126855 Neuroendocrinology 1995;61:326–336
          10.1159/000126855
          7898638
          © 1995 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: 11
          Categories
          Regulation of Gonadotropins

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