Fig. 3.

Bidirectional communication between central and peripheral tissue clocks. Temporal cues controlled by the central pacemaker (SCN) and other CNS clocks such as glucocorticoid and melatonin secretion, autonomic inputs, and body temperature are known to affect the molecular clocks in peripheral organs. At the same time, peripheral clocks, through molecules like leptin, ghrelin, FGF21, and adiponectin can feed back on the SCN and other brain region clocks. The overall result of this entangled communication network is an integrated rhythmic control of behavior and metabolic outputs. In this figure, it is didactically represented the phase (day or night) in which each factor has its highest value in humans