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Taste of fructose
By Rachel Ehrenberg
Scientists have a greater appreciation of
fructose’s full flavor. The sugar, which is
found predominantly in fruit, honey and
high-fructose corn syrup, tickles taste
cells found on the pancreas. The interaction can crank up the body’s secretion
of insulin, which may be a concern for
people prone to diabetes, researchers
report in the Feb. 21 Proceedings of the
National Academy of Sciences.
Experiments with mouse and human
cells and with living mice reveal that
fructose activates the same proteins in
pancreatic cells that the tongue uses
to taste sweets. When these cells are
exposed to glucose — the sugar that is the
body’s main source of energy — and then
get a hit of fructose, the cells pump out
more insulin than with glucose alone,
the researchers found.
Sleeplessness agitates the brain
Boost in electrical activity may explain why we need shut-eye
By Laura Sanders
Sleep deprivation makes the brain
groggy, but as waking hours mount nerve
cells actually grow increasingly jumpy, a
new study shows.
This amped-up state may explain why
seizures and hallucinations can accompany all-nighters. More generally, the
results help clarify what goes wrong in
a brain deprived of shut-eye.
“It’s an important finding,” says
neuroscientist Christopher Colwell of
UCLA. “Sleep deprivation is an area of
huge interest because most of us do not
get enough sleep.”
By subjecting six people to a night of
sleep deprivation and measuring their
brain responses, Marcello Massimini of
the University of Milan and colleagues
found that people’s brains become more
reactive as waking hours accumulate.
stronger than they were the previous
day, the scientists report online February 7 in Cerebral Cortex. This overreaction disappeared after a night’s sleep.
The results offer support for a theory
of why people sleep: During waking
hours, the brain accumulates connections between nerve cells as new things
are learned. Sleep then sweeps the brain
of extraneous clutter, leaving behind
only the most important connections.
Enhanced excitability in the brain
may explain why sleep deprivation can
The new results also have an intriguing link to depression. For some people,
sleep deprivation can quickly reverse
symptoms of depression, an effect that
may be due to the brain’s boosted excitability, Massimini says.
TYRBERG LAB/SANFORD-BURNHAM MEDICAL RESEARCH INSTITUTE