Gluconeogenesis is defined as the production of glucose from non-carbohydrate sources. Maintenance of blood glucose is important, as it is the main fuel for the brain and red blood cells. In the fasted state, carbohydrate stores (in the form of liver glycogen) are depleted in 12-24 h. Therefore, alternative substrates are required for glucose synthesis by gluconeogenesis. The main substrates are amino acids (muscle breakdown), glycerol (triacylglyc-erol) and lactate (anaerobic metabolism in skeletal muscle and red blood cells). The liver is the main site of gluconeogenesis, but it also occurs in the renal cortex during prolonged starvation. Fat cannot be converted into glucose, but instead is used for ketone production, which the brain utilizes as an energy source in prolonged starvation.
Was this article helpful?