Major Advances in Brain Glycogen Research: Understanding of the Roles of Glycogen Have Evolved from Emergency Fuel Reserve to Dynamic, Regulated Participant in Diverse Brain Functions.

Brain glycogen is extremely difficult to study because it is very labile to physiological status and postmortem autolysis, and glycogen degradative enzymes are rapidly activated by metabolites and signaling molecules. Glycogen is predominantly located within astrocytes in adult brain, and abnormal glycogen metabolism in neurons has lethal consequences. Diverse distribution of glycogen among subcellular compartments suggests local regulation and different functional roles, and recent studies have revealed critically important roles for glycogen in normal brain function and Lafora disease. This brief overview highlights some of the major advances in elucidation of glycogen's roles in astrocytic functions and neurotransmission and the severe consequences of aberrant neuronal glycogen metabolism.