Multi-photon microscopy scans by Cornell University biophysicists of living brain tissue, as reported in the latest issue of Science (July 2, 2004), reveal exactly how and when neurons (the cells that do the thinking) and astrocytes (the starburst-shaped glial cells that service neurons) interact to burn oxygen and glucose, after astrocytes make lactate from glucose in the bloodstream, to meet the extraordinary energy demands of the brain.
Based on imaging of two different energy states of NADH (nicotinamide adenine dinucleotide, a coenzyme involved in brain-cell metabolism), the Cornell biophysicists say they have both confirmed and redefined the controversial "astrocyte-neuron lactate shuttle" hypothesis for brain energy metabolism.
"Over the past decade scientists have passionately debated whether the activated brain burns glucose completely to water or incompletely to lactate," said Karl A. Kasischke, M.D., lead author of the Science paper titled "Neural Activity Triggers Neuronal Oxidative Metabolism Followed by Astrocytic Glycolysis." "Our results unify existing contradictory opinions and should be a win-win situation for both factions," said Kasischke, who is a research associate in the Developmental Resource for Biophysical Imaging and Opto-electronics (DRBIO) laboratory headed by Watt W. Webb. Webb, Cornell's S.B. Eckert Professor in Engineering and a co-inventor of multiphoton microscopy who also is an author on the Science paper, explains: "Multiphoton microscopy imaging of intrinsic fluorescence in NADH shows that early oxidative metabolism in neur
Contact: Roger Segelken
Cornell University News Service