Glycogen, the branched polymer of glucose is found mainly in the liver and muscle
in mammals. Along with several other proteins, glycogen forms separate cellular organelles,
and particles in cells. Glycogen particles in the liver have a special metabolic and
also regulatory connection to the intracellular endomembrane system, particularly
the endoplasmic reticulum. This connection is part of the organelle homeostasis in
hepatocytes and forms a “glycogenoreticular system”. The actual size of hepatic glycogen
stores and the rate of glycogenolysis determines several essential liver-specific
metabolic processes, such as glucose secretion for the maintenance of blood glucose
levels or the glucuronidation of certain vital endo-, and xenobiotics, and are also
related to liver antioxidant defense. In starvation, and in certain physiological
and pathological states, where glycogen stores are depleted, functions of the glycogenoreticular
system are altered. The starvation-induced depletion of hepatic glycogen content changes
the biotransformation of various endo- and xenobiotics. This can be observed especially
in acute DILI (drug-induced liver injury) due to paracetamol overdose, which is the
most common cause of acute liver failure in the West.
