Study: Metabolism in the brain fluctuates with circadian rhythm

The rhythm of life is driven by the cycles of day and night, and most organisms carry in their cells a common, (roughly) 24-hour beat. In animals, this rhythm emerges from a tiny brain structure called the suprachiasmatic nucleus (SCN) in the hypothalamus.

Take it out of the brain and keep it alive in a lab dish and this ''brain clock'' will keep on ticking, ramping up or gearing down production of certain proteins at specific times of the day, day after day.

A new study reveals that the brain clock itself is driven, in part, by metabolism, the production and flow of chemical energy in cells. The researchers focused primarily on a phenomenon known as ''redox'' in tissues of the SCN from the brains of rats and mice.

Redox represents the energy changes of cellular metabolism (usually through the transfer of electrons). When a molecule gains one or more electrons, scientists call it a reduction; when it loses electrons, they say it is oxidized. These redox reactions, the researchers found, oscillate on a 24-hour cycle in the brain clock, and literally open and close channels of communication in brain cells.

They report their findings in the journal Science.

''The language of the brain is electrical; it determines what kind of signals one part of the brain sends to the other cells in its tissue, as well as the other parts of the brain nearby,'' said University of Illinois cell and developmental biology professor Martha Gillette, who led the study.