In order to clarify the mechanisms underlying the surfactant-induced dehydration of the stratum corneum (SC), we first examined the constitutive water-holding function of the SC by removing intercellular lipids as well as hygroscopic materials from intact human SC. The dehydration of the SC can be easily induced by depletion of intercellular lipids, but was not affected by an additional water treatment, which releases a large amount of hygroscopic materials including amino acids. Consistent with this, the application of isolated intercellular lipids or their subfractions to the lipid-depleted and dehydrated SC rescues the decreased water content as well as marked scaling, although glycerine did not have such an effect. Parallel differential scanning calorimetry analysis revealed that lipid depletion causes the SC to reduce the nonfreezable bound water content and that application of isolated intercellular lipids recovered the bound water content up to the control level. On the other hand, the additional release of hygroscopic materials from lipid-depleted SC did not affect the bound water content. Based upon the above constitutive water-holding mechanism in the SC, we assessed the physicochemical mechanisms involved in surfactant-induced dehydration of the SC, leading to tight sensation and skin roughness. Similar to treatment with acetone/ether, treatment with surfactant releases a significant amount of intercellular lipids, the intensity of which varies among various surfactants but correlates well with the intensity of the induced dehydration of the SC leading to the tight skin sensation and skin roughness. Recovery or inhibition experiments revealed that the dehydration of the SC induced by surfactant treatment is significantly attenuated by the application of isolated intercellular lipids or by the addition of monoglyceride (MG) during the washing process, which results in a significant reduction in skin roughness. The latter study showed that whereas the release of sebum components and amino acids during surfactant treatment is not affected by the addition of MG, the removal of ceramides is significantly attenuated by the addition of MG, which suggests an essential role for ceramide depletion in the induction of the surfactant-induced dehydration of the SC. In conclusion, the above findings collectively suggest that the ceramide content in the SC is strongly associated with the regulation of SC hydration and that its deficiency due to surfactant treatment is essentially responsible for the surfactant-induced dehydration of the SC. This hypothesis is further strengthened by the fact that synthetic pseudoceramides are remarkably effective in preventing or abolishing the dehydration of the SC which is an intrinsic factor for inducing the tight sensation and roughness of the skin and which provides a pathological basis for atopic dry skin.

Keywords:
Stratum corneum, Dehydration, Surfactant, Bound water, Ceramides, Intercellular lipids, Amino acids, Water-holding function
This content is only available via PDF.
© 2004 S. Karger AG, Basel
2005
Copyright / Drug Dosage / Disclaimer
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.
You do not currently have access to this content.