+1 Recommend
1 collections
      • Record: found
      • Abstract: found
      • Article: found

      Influence of Calcium Ions on Proopiomelanocortin mRNA Levels in Clonal Anterior Pituitary Cells

      Read this article at

          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.


          The concentration of mRNA encoding proopiomelanocortin (POMC) was measured in AtT-20/D-16v cells, a clonal pituitary tumor cell line. Treatment of the cells with potassium (20 m M) or veratridine (10 µ M) for 12, 24 and 48 h caused a time-dependent increase in the levels of POMC mRNA which became significant after 24 h. These effects were not seen in the presence of the sodium channel blocker tetrodotoxin (5 µ M). In addition, the calcium channel blocker verapamil (10 µ M) completely abolished the responses to either potassium or veratridine, whereas the calcium channel agonist Bay K 8644 (0.1µ M) potentiated the effect of potassium. Furthermore, the calcium channel blockers verapamil (10 µ M) and nidefipine (1 µ M) significantly decreased not only basal levels of POMC mRNA but also the increase of mRNA levels induced by corticotropin-releasing factor (CRF; 0.1 µ M), 8-bromo-cAMP (1 m M) or cholera toxin (100 ng/ml). The drug-induced alterations in the mRNA POMC levels of the cells were, in each case, associated with similar alterations of immunoreactive β-endorphin in the medium. These results indicate that membrane depolarization to activate sodium channels and calcium channels initiates an entry of calcium ions which triggers POMC gene expression in the AtT-20 cells. Moreover, calcium entry into the cells may exert a tonic stimulatory effect on POMC mRNA under basal conditions and may also contribute to the enhancing effect of CRF or cAMP on POMC mRNA in these cells.

          Related collections

          Author and article information

          S. Karger AG
          02 April 2008
          : 47
          : 1
          : 32-37
          aPhysiologisches Institut der Universität München, Munich, and bDepartment of Neuropharmacology, Max-Planck-Institut für Psychiatrie, Martinsried, FRG
          124887 Neuroendocrinology 1988;47:32–37
          © 1988 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
          Original Paper


          Comment on this article