In mammals, a central circadian clock in the suprachiasmatic nucleus (SCN) of the brain coordinates circadian changes in physiology and synchronizes other peripheral clocks. T. A. Wang et al. (see the Perspective by Belle and Piggins) report that daily changes in electrical activity of neurons in the SCN are coupled to the circadian clock through changes in metabolism—in particular, changes in reduction and oxidation state within the cell that reflect daily cycles of metabolism. The conductance of two kinds of potassium channels in the neurons was sensitive to redox state, thus linking the membrane potential and firing rate of the neurons to cycles of metabolic activity.
T. A. Wang, Y. V. Yu, G. Govindaiah, X. Ye, L. Artinian, T. P. Coleman, J. V. Sweedler, C. L. Cox, M. U. Gillette, Circadian rhythm of redox state regulates excitability in suprachiasmatic nucleus neurons. Science 337, 839–842 (2012). [Abstract] [Full Text]