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      Inhibition of Decrease in Natural Killer Cell Activity in Repeatedly Restraint-Stressed Mice by a Biological Response Modifier Derived from Cultured Mycelia of the Basidiomycete Tricholoma matsutake

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          Abstract

          Objective: To develop a method to cope with stress-induced reduction in immunocompetence, we evaluated the immunomodulatory activities of a biological response modifier derived from the mycelia of the basidiomycete Tricholoma matsutake (CM6271) in mice under repeated restraint stress. Methods: C57BL/6 mice were inserted, one per tube, into 50-ml polypropylene tubes into which more than 30 ventilation holes had been drilled, and were restrained everyday for 20 days in this fashion for set periods of time. Natural killer (NK) cell activity and NK1.1-positive cell counts in the spleen, ACTH and corticosterone levels in the blood were determined. CM6271 was orally administered daily during the restraint stress period. Results: (1) When the mice were restrained in a confined space for 6 h per day for 20 days, the NK cell activity and the NK1.1-positive cell counts in the spleen significantly decreased after day 5 with an increase in the blood ACTH and corticosterone levels. (2) Oral administration of CM6271 during the restraint stress period significantly prevented the stress-induced decrease in NK cell activity. The effect was dependent on the timing, duration, and doses administered. (3) CM6271 did not significantly affect the splenic NK1.1-positive cell counts or the levels of blood ACTH and corticosterone in restraint-stressed mice. Conclusion: The above findings suggest that CM6271 inhibits the restraint stress-induced decrease of NK cell activity in a timing of administration and dose-dependent manner.

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          Most cited references 8

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          Lesions of the posterior paraventricular thalamus block habituation of hypothalamic-pituitary-adrenal responses to repeated restraint.

          We examined the role of the posterior division of the paraventricular nucleus of the thalamus (pPVTh) in habituation of hypothalamic-pituitary-adrenal (HPA) responses to repeated restraint. Habituation refers to the decrement in HPA activity that occurs with repeated exposure to the same or homotypic stressor. To date, the pPVTh has been shown to inhibit the enhanced or facilitated HPA responses to novel, heterotypic restraint in previously chronically cold stressed rats. We hypothesized that the pPVTh also inhibits HPA activity under conditions of habituation. In the first experiment, we lesioned the pPVTh and examined adrenocorticotropic hormone (ACTH) and corticosterone responses to the first or eighth restraint exposure. In sham-lesioned rats, we found lower ACTH and corticosterone responses to the eighth period of 30 min restraint compared to the first exposure, evidence for habituation. In pPVTh-lesioned rats, there was no difference in ACTH and corticosterone responses to the eighth compared to the first restraint exposure. Therefore, pPVTh lesions prevented the habituation of HPA responses to repeated restraint. In the second experiment, we examined whether habituation to restraint is observable in response to an acute, single restraint on day 28 in sham and pPVTh lesioned rats that were exposed to restraint only on days 1 through 8. In this experiment, we replicated the results from the first experiment, and found evidence that habituation to restraint can be observed weeks after chronic stress has been terminated. Furthermore, pPVTh lesions had no additional effects on HPA responses to acute stress on day 28. In summary, pPVTh lesions inhibit habituation of HPA activity to a homotypic stressor, without altering HPA responses to the first restraint. Thus, the intact pPVTh inhibits HPA activity under conditions of habituation, as well as facilitation, and represents an important regulator of HPA activity under conditions of chronic stress.
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            Effects of chronic mild stress on lymphocyte proliferative response. Participation of serum thyroid hormones and corticosterone.

            There is increasing evidence that stress produces changes in various immune processes. Some of these changes may be due to neurochemical and hormonal alterations including thyroid hormones levels. This work was carried out to study the impact of chronic mild stress (CMS) exposure on proliferative responses and its correlation with serum thyroid hormone levels. In addition, the influence of serum corticosterone levels on these responses was also studied. For this purpose, mice were submitted from1 to 6 weeks to a CMS model. After undergoing the stress schedule for 4 weeks, an alteration in the proliferative response was observed. Lymphocytes from exposed animals showed a decrease in T-cell response to concanavalin-A (Con A) and phytohemagglutinin (PHA) and an increase in B-cell proliferation to lipopolysaccharides (LPS). In parallel, a reduction in T3 and T4 serum levels was observed. On the contrary, serum corticosterone levels increased in animals exposed to CMS for 1 or 2 weeks and then return to normal values. Lowering serum thyroid hormone levels by propylthiouracil (PTU) treatment negatively modulates T-cell response without affecting B-cell response. On the other hand, the substitutive T4 treatment in stressed animals improved significantly the proliferative T-cell response. Non-significative changes in CD4/CD8 ratio were observed neither in stressed, PTU- or T4-treated animals. Taken together, our results suggest an impact of chronic stress on thyroid function that in turn alters T-cell response. These findings may help to elucidate the physiological mechanisms through which stress plays a roll in the etiology of many diseases.
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              Are adhesion molecules involved in stress-induced changes in lymphocyte distribution?

              Acute psychological stress is associated with important changes in circulating cell populations and reductions in cell-mediated immune responses. However, the mechanisms underlying these phenomena are poorly understood. In this study, we investigated (i) acute and chronic restraint stress effects in Sprague-Dawley rats on peripheral lymphocyte subsets and (ii) adhesion molecule (beta2 integrins) expression and (iii) also determined whether glucocorticoids could underlie stress-related changes in cellular redistribution. We observed time-dependent changes in lymphocyte distribution including decreased (-21%) percentages of peripheral T helper cells and increased (88%) NK cell numbers following acute brief restraint. Acute stress was also found to overall upregulate beta2-integrin (CD11a and CD11b) expression on T cells and to raise (1049%) plasma corticosterone levels. However, this stress response was found habituated (-75% vs. acute) in the animals previously exposed to chronic restraint stress. Stress effects on circulating lymphocytes were not observed in animals previously exposed to chronic intermittent restraint stress or chronically stressed animals re-exposed to the same stressor. Our results indicate that 1) stress alters lymphocyte distribution, 2) that adhesion molecules may be involved in stress-induced alterations of T-cell distribution and 3) that these changes may be related to circulating glucocorticoids and subjected to adaptation with repeated stress exposure.
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                Author and article information

                Journal
                NIM
                Neuroimmunomodulation
                10.1159/issn.1021-7401
                Neuroimmunomodulation
                S. Karger AG
                1021-7401
                1423-0216
                2004
                October 2003
                17 October 2003
                : 11
                : 1
                : 41-48
                Affiliations
                aDepartment of Hygiene and Public Health (I), School of Medicine, Tokyo Woman’s Medical University, and bBiomedical Research Laboratories, Kureha Chemical Industry Company Limited, Tokyo, Japan
                Article
                72968 Neuroimmunomodulation 2004;11:41–48
                10.1159/000072968
                14557678
                © 2004 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
                Figures: 4, References: 35, Pages: 8
                Categories
                Original Paper

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