[Disrupted circadian rhythms and senescence].

Aging alters a broad spectrum of physiological, endocrine, and behavioral rhythms, and the close relationship between age-associated disease and disrupted circadian rhythms has been shown. Circadian rhythms are regulated by a set of clock genes and mutations in clock genes result in short life in animal models. The sirtuin family is involved in the regulation of many physiological functions, including gene transcription, energy metabolism, cell senescence(definition) and oxidative stress, and has recently been associated with regulation of circadian clock gene expression. Impaired circadian rhythmicity is related to a decrease of NO production with aging, suggesting the important role of NO for age-associated diseases. Furthermore, senescence decreases the ability of cells to transmit circadian signals to their clocks.