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      Growth Hormone Responsiveness in vivo and in vitro to Growth Hormone Releasing Factor in the Spontaneously Diabetic BB Wistar Rat

      a , b

      Neuroendocrinology

      S. Karger AG

      Growth hormone, Growth hormone releasing factor, Diabetes

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          Abstract

          In order to determine whether there is an abnormality in the pituitary responsiveness to GRF in the diabetic rat, we examined the in vivo and in vitro effects of hGRF-44 NH2 (hGRF) on growth hormone (GH) release in the spontaneously diabetic BB Wistar rat. Under pentobarbital anesthesia, hGRF was injected intravenously at a dose of 500 ng/kg in male diabetic BB Wistar rats (n = 11) and in male control Wistar rats matched for weight (n = 11). Basal serum GH concentrations were significantly lower in the diabetic group, (123 ± 5 ng/ml, mean ± SEM) than in the control group (362 ± 15 ng/ml). However, the GH response to hGRF was significantly greater in the diabetic group (GH increment 873 ± 153 ng/ml) than in the control group (268 ± 91 ng/ml). The effect of hGRF was further tested in a perifusion system of freshly dispersed anterior pituitary cells of diabetic BB Wistar rats and control Wistar rats. Basal secretion rate of GH from cells of diabetic rats (0.85 ± 0.06 µg/2 pituitaries · 2 min) was lower than that from cells of control rats (1.60 ± 0.18 µg/2 pituitaries · 2 min). The GH response to 2-min pulses of hGRF at concentrations of 1.56, 6.25, and 25 pM with and without somatostatin 10<sup>–9</sup> M was significantly greater in the diabetic group than in the control group. In conclusion, there is in the spontaneously diabetic rat an increased in vivo and in vitro GH responsiveness to exogenous hGRF suggesting an abnormality of GH regulation at the pituitary level.

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          Author and article information

          Journal
          NEN
          Neuroendocrinology
          10.1159/issn.0028-3835
          Neuroendocrinology
          S. Karger AG
          0028-3835
          1423-0194
          1987
          1987
          02 April 2008
          : 46
          : 2
          : 162-166
          Affiliations
          aMetabolic Unit and bLaboratory of Neuroendocrinology, Centre de Recherche, Hôpital Notre-Dame, Université de Montreal, Montreal, Canada
          Article
          124814 Neuroendocrinology 1987;46:162–166
          10.1159/000124814
          2888037
          © 1987 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: 5
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          Original Paper

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