Hypothalamic expression of the GCK gene plays an important role in the regulation of dietary glucose intake in particular, and overall feeding behavior in general. The primary hypothalamic cells expressing glucokinase are within the arcuate nucleus, ARC. Expression of the hypothalamic GCK gene increases specifically within the ARC in response to fasting. Manipulation of GCK expression within the ARC of experimental animals alters glucose intake. Increased GCK expression in the ARC results in increased glucose ingestion, whereas, decreased GCK expression results in reduced glucose ingestion. These observations indicate that ARC expression of GCK underlies the phenomenon of carbohydrate craving.
But in living organisms, the oxidation of glucose contributes to a series of complex biochemical reactions which provides the energy needed by cells. The first step in the breakdown of glucose in all cells is glycolysis , producing pyruvate which is the starting point for all other processes in cellular respiration . In cells where oxygen is present ( aerobic respiration ) these processes have been modeled in the TCA or Krebs cycle . A major part of the use of the energy from glucose oxidation is the conversion of ADP to ATP , with the energy-rich molecule ATP being subsequently used as the energy currency of the cell.