gluconeogenesis

Last reviewed 01/2018

Gluconeogenesis is the synthesis of glucose from non-carbohydrate precursors e.g.:

• lactate
• glycerol
• pyruvate
• certain amino acids

Gluconeogenesis occurs predominantly in the liver; it can also occur in the renal cortex. The pathway contains many enzymes which are active in glycolysis. However, gluconeogenesis is not simply a reversal of glycolysis as the enzymes pyruvate kinase, 6-phosphofructokinase and hexokinase have their equilibrium in favour of the forward reaction. New enzymes need to be recruited to the cause.

Gluconeogenesis has a key role in the maintenance of blood glucose levels during certain stresses e.g. prolonged starvation. After 12-24 hours of fasting, glycogen reserves are depleted and the body reverts to gluconeogenesis to supply glucose for tissues with an obligatory dependence e.g. the brain.