Circadian Regulation of Hormesis for Health and Longevity

Abstract

In mammals the circadian rhythms are regulated by the suprachiasmatic nucleus (SCN), pacemaker/main clock located in the hypothalamus. The SCN synchronizes and entrains the physiological, endocrine, neural, and behavioral activities of mammals to the daily light/dark cycles via close interaction of core circadian machinery with a network of interconnected transcriptional and translational feedback loops that regulate melatonin synthesis in pineal. Such a molecular framework is also present in every other peripheral cell/tissue/organ called peripheral clock and is synchronized to main clock/SCN. The stoichiometric alterations between pacemaker and peripheral clocks in the neural and temporal organization result in circadian dysfunction. Many physiological processes follow a hormetic response and several factors are involved in inducing an adaptive response. Biological responses are adaptive mechanisms influenced by not only the dose or the compound, but also time. Aging leads to the disturbance in the functional integrity of circadian timing system (CTS) otherwise capable of coping with the alterations in environment and oxidative stress, thus resulting in sleep disorders, neurodegenerative disorders, cardiovascular diseases, cancer, and metabolic diseases etc. Thus, regulating CTS can increase adaptability, a step toward good health and longevity.Advanced knowledge about the hormetic responses will open new avenues to promote health interventions aimed at increasing capacity for adaptability.