Biologische Uhren in der Koordination zentraler und peripherer physiologischer Prozesse

A ubiquitous network of cellular circadian clocks regulates physiology and behavior along the 24-hr day cycle. A central pacemaker located in the suprachiasmatic nucleus (SCN) of the hypothalamus aligns endogenous rhythms with the external light-dark cycle. Via neuronal and humoral signals the SCN resets subordinate clocks in central and peripheral tissues and, in this way, coordinates different physiological processes throughout the body. Modern life styles frequently lead to disruptions of the endogenous clock system, increasing the risk for several metabolic and neuro-psychiatric disorders. The hormones melatonin and cortisol are important factors in the stabilization of the circadian clock system, serving as internal zeitgebers of peripheral and central rhythms. Chrono-Therapies such as daytime-Adjusted drug application or the stabilization of endogenous rhythms by timed zeitgeber application have preventive as well as curative potential and may become important tools as supplements for more conventional therapies, in particular for chronic diseases.