X-Message-Number: 24328
From: "Basie" <>
Subject: Laser microscopy technique settles long debate 
Date: Sun, 4 Jul 2004 16:41:09 -0400

Laser microscopy technique settles long debate about brain chemistry, could
aid studies of Alzheimer's and stroke damage, Cornell biophysicists report
EMBARGOED UNTIL THURSDAY, JULY 1, 2004, 2 P.M., EST
Contact: Roger Segelken
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Starburst-shaped astrocytes (red cells) and neurons (blue cells) were
labeled with specific antibodies in this fixed rat brain section. Because
NADH, the coenzyme involved in brain metabolism, fluoresces differently in
astrocytes and neurons in living brain tissue, biophysicists at Cornell
could determine precisely when astrocytes were providing extra lactate
'fuel' to neurons, confirming the controversial astrocyte-neuron lactate
shuttle hypothesis. Copyright   Credit: K. Kasischke,P. Fisher/Cornell
University Click on the image for a high-resolution version (2.9MB)

Proof of activity-dependent metabolism in two kinds of brain cells, neurons
undergoing oxidative metabolism show up as green speckles while astrocytes
with glycolytic metabolism are red in this multiphoton microscopy scan of
living rat brain tissue. Copyright   Credit: K. Kasischke/Cornell DRBIO
ITHACA, N.Y. -- A laser-based microscopy technique may have settled a
long-standing debate among neuroscientists about how brain cells process
energy -- while explaining what's really happening in PET (positron emission
tomography) imaging and offering a better way to observe the damage that
strokes and neurodegenerative diseases, such as Alzheimer's, wreak on brain
cells.

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.

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