Vitamin D and Its Hydroxylated Metabolites in the Rat

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Abstract

Replacing body stores of vitamin D in pregnant rats with radiolabelled cholecalciferol, enabled the measurement of cholecalciferol and its hydroxylated metabolites in fetal tissue. Elevated levels of 24, 25-dihydroxycholecalciferol were found to be present in fetuses, with highest accumulation in the skeleton. A similar finding was observed when tritiated 24,25-dihydroxycholecalciferol was administered continuously to pregnant rats. When tritiated 1,25-dihydroxycholecalciferol was administered, very little was transported into the fetuses, and out of the transported fraction a major portion was found to be esterified. A selectivity pattern was established for the lacteal transport of cholecalciferol and its hydroxylated metabolites, in the order: cholecalciferol > 25-hydroxycholecalciferol > 24,25-dihydroxycholecalciferol > 1,25-dihydroxycholecalciferol. Vitamin D sulfoconjugates were not detected in suckling rat pups, and over 80% of the lacteal-transported 1,25-dihydroxycholecalciferol in suckling pups was found to be esterified. It is suggested that rat fetuses and newborn pups do not require 1,25-dihydroxycholecalciferol, that a protective mechanism against vitamin D intoxication operates in fetuses and pups in the form of esterifying enzymes, and that 24,25-dihydroxycholecalciferol might be associated with bone metabolism.

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Journal

Journal ID (publisher-id): HRE

Journal ID (nlm-ta): Horm Res Paediatr

Journal ID (doi): 10.1159/issn.1663-2818

Title: Hormone Research in Paediatrics

Publisher: S. Karger AG

ISSN (Print): 1663-2818

ISSN (Electronic): 1663-2826

Publication date Subscription-year: 1978

Publication date (Print): 1978

Publication date (Electronic): 25 November 2008

Volume: 9

Issue: 5

Pages: 292-300

Affiliations

Biochemistry Department, The Weizmann Institute of Science, Rehovot

Article

Publisher ID: 178924 Other ID: Horm Res 1978;9:292–300

DOI: 10.1159/000178924

PubMed ID: 210099

SO-VID: d405514e-bf0c-4670-ab04-8e2fc3811e9a

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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.

History

Date received : 16 December 1977

Date accepted : 01 March 1978

Page count

Pages: 9

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