Cont.
03 Stress and Glucose Metabolism
- Under normal conditions the gluconeogenesis occurs during starvation to supply glucose to the cells, especially the brain which is dependent on the glucose. Stress increases the hepatic glucose production by increasing the activities of key gluconeogenic enzymes: phosphoenol pyruvate carboxy kinase (PEPCK), pyruvate carboxylase, fructose 1,6 bisphosphatase (FBPase) and glucose-6-phosphatase (G6Pase). All these key regulatory enzymes are transcriptionally regulated by glucocorticoids.
- Glucocorticoids also stimulate the expression of pyruvate carboxylase and glucose-6-phosphatase. In addition stress increases the activities of aminotransferases, glutamic pyruvic transaminase (GPT) and glutamic oxaloacetatic transaminase (GOT) which further increase the concentration of substrates like pyruvate and oxaloacetate for gluconeogenesis.
- Glucocorticoids are known to increase the blood glucose levels under stressful conditions by not only increasing gluconeogenesis but also by reducing insulin sensitivity. The glucocorticoids exert this action by antagonizing insulin stimulated translocation of glucose transporters from intracellular compartments to plasma membrane.
