Memory function and brain glucose metabolism.

Memory formation and memory retrieval are subject to complex cellular and molecular processes. Increasing evidence exists that neuronal glucose metabolism and its control by the insulin signal transduction cascade are the main players in such processes. Acetylcholine synthesis depends on the availability of acetyl CoA, provided from glucose breakdown, and insulin, which controls the activity of acetylcholine transferase. ATP is necessary for both synaptic activity and plasticity. This is also true for APPs, the secreted derivative of APP. Trafficking of the latter protein is controlled by insulin and insulin receptor function also acting on activity-regulated cytoskeleton-associated gene expression, which induces biochemical stimuli involved in synaptic activity and plasticity. Any damage in neuronal glucose metabolism and its control may, therefore, cause disturbances in memory function--as is found for example in sporadic Alzheimer's disease. Mimicking these metabolic and behavioral abnormalities in experimental animals, it was found that EGb 761 (definition see editorial) shows beneficial effects both on brain glucose and energy metabolism and on behavior.