Elsevier

Experimental Gerontology

Volume 32, Issues 4–5, July–October 1997, Pages 415-429
Experimental Gerontology

Plasticity of neuroendocrine-thymus interactions during aging

https://doi.org/10.1016/S0531-5565(96)00166-0Get rights and content

Abstract

Thymic regrowth and reactivation of thymic endocrine activity may be achieved even in old animals by different endocrinological or nutritional manipulations such as, (a) intrathymic transplantation of pineal gland or treatment with melatonin, (b) implantation of a growth hormone (GH) secreting tumor cell line or treatment with exogenous GH, (c) castration or treatment with exogenous luteinizing hormone-releasing hormone (LH-RH), (d) treatment with exogenous thyroxine or triiodothyronine, and (e) nutritional interventions such as arginine or zinc supplementation. These data strongly suggest that thymic involution is a phenomenon secondary to age-related alterations in neuroendocrine-thymus interactions and that it is the disruption of such interactions in old age that is responsible for age-associated dysfunction. With regard to the mechanisms involved in hormone-induced thymic reconstitution, it is at present, difficult to draw any definitive conclusions. The effect of GH, thyroid hormones, and LH-RH may be due to the presence on thymic epithelial cells supposed to produce thymic peptides, of the specific hormone receptors. Melatonin or other pineal factors may also act through specific receptors, but experimental evidence is still lacking. The role of zinc, whose turnover is usually reduced in old age, is diverse. The effects range from the reactivation of zinc-dependent enzymes, required for both cell proliferation and apoptosis, to the reactivation of thymulin, a zinc-dependent thymic hormone. The role of zinc may even be more crucial. According to recent preliminary data obtained both in animal and human studies, it appears that the above reported endocrinological manipulations capable of restoring thymic activity in old age, may act also by normalizing the altered zinc pool.

References (52)

  • M. Provinciali et al.

    Effect of melatonin and pineal grafting on thymocyte apoptosis in aging mice

    MAD

    (1996)
  • H.O. Besedovsky et al.

    Immune-neuroendocrine circuits: Integrative role of cytokines

  • A. Bonomo et al.

    Thymus epithelium induces tissues-specific tolerance

    J. Exp. Med.

    (1993)
  • K. Bulloch et al.

    The role of calcitonin gene-related peptide in the mouse thymus revisited

    Ann. NY Acad. Sci.

    (1994)
  • S.C. Cunanne et al.

    Alteration of tissue zinc distribution and biochemical analysis of serum following pinealectomy in the rat

    Endocrinol. Rev.

    (1979)
  • M. Dardenne et al.

    Neuroendocrine circuits controlling the physiology of the thymic epithelium

    Ann. NY Acad. Sci.

    (1992)
  • M. Dardenne et al.

    Contribution of zinc and other metals to the biological activity of the serum thymic factor

  • D.R. Davila et al.

    Role of growth hormone in regulating T-dependent immune events in aged, nude and transgenic rodents

    J. Neurosci. Res.

    (1987)
  • N. Fabris et al.

    Zinc, human diseases and aging

  • N. Fabris et al.

    Immunomodulating role of growth hormone

  • N. Fabris et al.

    Hormones

  • N. Fabris

    Biomarkers of aging in the neuroendocrine-immune domain

  • N. Fabris

    Neuroendocrine-thymus interactions

  • N. Fabris

    Neuroendocrine/thymus interactions during development and aging

  • N. Fabris et al.

    Neuroimmunomodulation: The state of art

    Ann. NY Acad. Sci USA

    (1994)
  • N. Fabris et al.

    Thyroid function modulates thymus endocrine activity

    J. Clin. Endocrinol. Metab.

    (1986)
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