The Relationships of Age-Related Changes in the Biorhythms of the Thymus Endocrine Function and Pineal Melatonin-Producing Function in Healthy People

Abstract

The circadian and circannual rhythms play the main role in the adaptation of human immune and pituitary-adrenal systems functioning to the changing photoperiod. The rhythmicity of thymus endocrine function is an important part of the chronobiological organization of immune system. The pineal hormone melatonin is the central regulator of rhythms of healthy human organism functions and involves thymus hormones (namely FTS/thymulin) in synchronizing influence on the immune system functioning. Age-related changes of thymus hormone and melatonin rhythms in healthy people are linked and precede the aging desynchronosis of immune and pituitary-adrenal system functions. In healthy male versus female the above changes occur at earlier life periods and are more pronounced. The thymus endocrine function does not completely disappear in the elderly/old people and is able to respond to the synchronizing influence of melatonin with part of the adrenal gland. Age-related changes in the circadian and circannual rhythms of the thymus hormone, melatonin, immune system, and adrenal gland functions become more pronounced at the development of age-associated diseases (neurodegenerative, cardiovascular, oncological). Melatonin can be perspective medicine for restoration of disturbed rhythmicity of thymus, immune system, and adrenal glands in accelerated human aging and in patients with age-dependent diseases.