Scientists at Washington University in St. Louis found that hunger
causes needs for nutrition pressing need for sleep. Just like humans and rats,
fruit flies can not survive without sleep. However, in fruit flies engineered
to be sensitive to sleep deprivation, hunger could increase the survival time
without sleep almost tripled.
The researchers showed that the ability to withstand the effects of
sleep deprivation are linked to proteins that help brain of fruit flies
regulate the storage and use of lipids which are types of molecules including
fats such as cholesterol and vitamins are fat soluble vitamins A and D.
"The drugs commonly used to make people fall asleep or make
people stay awake, all targeted at a number of pathways in the brain, are all
related to neuro transmission," says Paul Shaw, PhD, assistant professor
of neurobiology and anatomy. "Modifying lipid processing with drugs can
give us a new way that is more effective or less side effects in tackling the
problem of sleep."
The study was published online on August 31 in PLoS Biology.
The discovery adds new challenges to the complex relationship
between sleep and metabolic diet. Scientists know of about a decade ago that
lack of sleep leads to obesity and contribute to the development of diabetes
and coronary disease. Until now, no one has linked the gene associated with the
regulation of lipid sleep needs.
Clay Semenkovich, MD who is an expert on lipid University of
Washington but not directly involved in the research, said that the results fit
with the growing understanding that organisms use lipids more than just energy
storage.
"It is increasingly clear that the fat serves as a signaling
molecule in a variety of contexts," says Semenkovich, the Herbert S.
Gasser Professor of Medicine. "If you identify the lipids involved in
sleep regulation and figure out how to control it, you can reduce the pain
associated with lack of sleep or the need to stay awake."
Shaw uses the fruit fly as a model the effects of sleep on higher
organisms. He was one of those who first proved that fruit flies enter a state
comparable to sleep, showing that fruit flies have periods of inactivity where
greater stimulation is required to rouse them. Just like humans, fruit flies
that lack of sleep one day will try to replace it by sleeping more the next
day, a phenomenon which is shown as a sleep debt. Fruit flies that lack of
sleep also showed reduced performance on a simple test of learning ability.
Research in the lab showed that hunger or hunger fast, resulting in
reduced sleep time. A more recent study also showed that hunger can change the
activity levels of genes that regulate lipid storage and use.
Shaw's lab previously demonstrated that fruit flies with a mutation
in the gene biological time accumulate sleep debt faster and begin to die after
stay awake at least 10 hours. Matt Thimgan, PhD, a postdoctoral research
fellow, reported in a newspaper that starving fruit flies spent more time awake,
and starving fruit flies with mutations in genes of biological time can last up
to 28 hours without sleep.
The scientists tested the flies from hunger and lack of sleep and
sleep debt two will sign an enzyme in saliva or saliva and the flies ability to
learn to associate a light with an unpleasant stimulus. Both test results
showed that the starving flies were not sleepy.
"From an evolutionary perspective, this makes sense,"
said Thimgan. "If you're hungry, you want to make sure cognitively that
you are on top of the game, to increase your chances of finding food rather
than becoming food for someone else."
Scientists found an effect similar to starvation in fruit flies
where a gene called lipid storage droplet 2 (LSD2) disabled. After sleep
deprivation, fruit flies with a mutation LSD2 less inclined to sleep in a long
time and still scored high on tests of learning.
"Mutant LSD2 seem to constantly rotate lipids through their
storage depot in cells, putting it into and remove it very quickly," said
Thimgan. "Disabling LSD2 seems to be making the cells difficult to
restrain lipids and use them properly, and we think it disturb the ability of
brain cells to respond to sleep deprivation."
Researchers are trying to identify the specific lipids affected
LSD2 loss.
Source: "http://sainspop.blogspot.co.id"
Sign up here with your email
ConversionConversion EmoticonEmoticon