Clock-to-Clock Communication

The SCN regulates central and periphery clocks by neuronal and humoral mechanisms. Via this clock-to-clock communication various physiological rhythms are coordinated with each other and synchronized to external time. We are interested in the mechanisms by which central and peripheral clocks are reset. Using surgical and genetic approaches we could show that clocks located in the adrenal cortex are reset via the autonomic nervous system and regulate glucocorticoid release into the blood. The adrenal clock controls the sensitivity of the steroidogenic machinery to endocrine signals form the pituitary. Microarray analyses have shown that more than 3,000 genes are clock regulated in the adrenal, many of which are involved in steroid biosynthesis. Disruption of clock rhythms damages this network, altering glucocorticoid levels in the blood. Glucocorticoids further play a role in transmitting time-of-day information to other peripheral organs. In this context we were able to show that adrenal glucocorticoid rhythms can be pharmacologically manipulated to speed up the adaptation of  the circadian system during jet lag.


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