A benefits some people report after going LC is clearer thinking
and needing less sleep. One of my long-time problems has been
not being able to go to sleep if I'm even slightly hungry. The
following article could be part of the reason for both.
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Research Reveals Blood Sugar's Effect on Wakefulness
By Steven Reinberg
HealthDay Reporter on 05/31/2006
WEDNESDAY, May 31 (HealthDay News) -- Ever notice that hunger can
sharpen your senses, while a full, satisfying meal leaves you
yearning for a nap?
The key to this response is the simple sugar glucose, and British
researchers have discovered how it works its neural magic.
In experiments with mice, the researchers determined how glucose
blocks neurons -- brain cells -- that regulate wakefulness. They
found that a class of potassium ion channels made up of proteins
in the cell membrane affects the cells' responses by controlling
the amount of potassium getting into the cells.
Then they wanted to find out how glucose inhibits a particular
class of glucose-sensing neurons that produce tiny proteins
called orexins, which regulate states of consciousness.
"The firing of consciousness-regulating brain cells is sensitive
to changes in glucose that occur between normal meals," said lead
researcher Denis Burdakov, a research fellow at the University of
Manchester. "Now we know how glucose can stop neurons from
firing, something which eluded neuroscientists for the last 30
years."
The findings appear in the June 1 issue of the journal Neuron.
Burdakov said it was known that glucose inhibits the activity of
orexin neurons; malfunction of these cells can lead to narcolepsy
and obesity. "Recently, it was discovered that these brain cells
promote wakefulness and when lost, lead to narcolepsy. But how
glucose does this was unknown," he added.
In its experiments, Burdakov's team used engineered mice to
produce a fluorescent protein only in orexin neurons. This
allowed the researchers to isolate the neurons in brain slices
from the mice and perform precise biochemical and
electrophysiological studies to explore how glucose acted on
those neurons.
Then the researchers did experiments exposing the neurons to the
subtle changes in glucose levels known to occur in daily cycles
of hunger and eating. They found that activation of a type of
potassium in the membrane of orexin neurons is responsible for
glucose's inhibitory action.
"This previously unknown mechanism of glucose-sensing is so
sensitive, it can detect minute changes in glucose levels that
occur, for example, between normal breakfast and lunch," Burdakov
said.
It seems that the activity of orexin neurons, which regulate
appetite and reward feelings, as well as wakefulness, can be
controlled by normal, daily changes in brain glucose levels,
Burdakov said. "This may provide a candidate explanation for
after-meal sleepiness and for why it is difficult to sleep when
hungry," he said.
The finding may also have implications for designing new drugs
that target this potassium channel, Burdakov said. "This could be
a treatment for disorders that involve orexin neurons and/or
brain glucose sensing, such as disorders of sleep and body weight
like obesity, anorexia, diabetes and narcolepsy," he said.
Christopher M. Sinton, an assistant professor of internal
medicine at the University of Texas Southwestern Medical Center,
Dallas, said, "This [glucose] mechanism is unexpected because it
is unusual, and the paper is a careful and exceptional
description of its discovery."
"Perhaps more importantly, however, we now know why orexin cells
can be so exquisitely sensitive to very small changes in
circulating glucose levels, and also how they respond very
rapidly to these changes," Sinton said. "Hence the activity of
orexin cells will be increased even by the relatively small
changes in glucose that occur for short periods between meals."
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