Chronobiology of the Gastrointestinal System

Abstract

Circadian clocks and biological rhythms have been known for billions of years. Nevertheless, only recently the mechanisms of their functioning, including characteristic rhythmical influence on the variety of physiological, metabolic and behavioral processes, have been understood. The above-mentioned rhythm is called a circadian rhythm. The clock mechanism consists of the central master pacemaker, located in the suprachiasmatic nucleus, and several peripheral oscillators, distributed also in the gastrointestinal tract, where it controls, among others, immunological processes and the integration of the mucosal barrier. The central pacemaker is entrained mostly by light. Peripheral oscillators receive directions from the central pacemaker, but other cues, including food, may also influence their function. Molecular components of the biological clocks are products of the clock genes. Maintaining the synchronization of the internal clock with 24-hour light-dark cycle requires distinct environmental cues, so-called "time givers". Any disturbances (desynchronization) in biological rhythms can lead to a variety of health problems, including disorders of gastrointestinal tract. These disturbances can be caused by different factors (night shift work, irregular food intake) or pathological conditions (e.g. inflammatory process) and can directly influence the expression of the clock genes. © 2010 Almamedia Press.