Age-related circadian disturbances in melatonin causing changes in thymus hormones and glucocorticoids rhythmicity in healthy animals and humans

Abstract

Circadian rhythms of the organism functions cause its adaptation to changes in environmental lighting. The pineal gland is a key regulator of the circadian rhythms of the immune system. The thymus, its central organ, is the source of some hormones, in particular, the highly active thymic serum factor / thymulin. Therefore, the issues of age-related changes in the circadian intra-immune relationships with thymus involvement and the possibility of melatonin influence not only on the above links but also on the glucocorticoids hormones with adaptive effect require an in-depth analysis. Discussed are the literature data and our own findings how age-related changes in the circadian rhythms of thymus endocrine and adrenal gland glucocorticoid functions are linked with the melatonin-forming function of the pineal gland in healthy animals of different species (mice, rats, rabbits) and humans. The similar manifestations of the above interactions in healthy animals and humans demonstrate the biological significance of the pineal gland for the supporting circadian rhythms of the thymus and adrenal gland functions in the adult organism. The correlation of age-related changes in circadian rhythmicity of pineal gland in healthy animals and human, on the one hand, with the thymus and adrenal glands, on the other hand, has been demonstrated. In addition, the decrease of age-related disorders in the thymulin and glucocorticoid blood levels under the influence of pineal gland factors (melatonin and peptides) was shown. Thus, (a) the thymus endocrine function does not completely disappear in the old organisms and it responds to the effects of melatonin and peptide factors of the pineal gland and (b) age-related pineal gland desynchronosis has pathogenic significance for the formation of circadian disturbances in the thymus hormones and glucocorticoids.