Jet Lag Leaves Kidneys In Another Time Zone
|
|
Jet lag. CREDIT: dreamstime |
WASHINGTON (ISNS) -- Human beings aren't built to cross time zones. After an
international flight, it takes days for the body to overcome the fatigue and
nausea of jet lag, the biological price of doing business in the modern
world.
That's because every organ keeps time with its own separate clock.
Though the brain tries to synchronize all of these clocks on a daily basis, some
are more stubborn about resetting than others when adjusting to a new time zone
and sleep schedule -- according to a new study of sleep-deprived mice, which
have internal clocks similar to ours.
"Jet lag is a big mess of different
clocks," said Gregor Eichele of the Max Planck Institute of Biophysical
Chemistry in Gottingen, Germany.
A transcontinental traveler's brain may
adjust to being in Paris the day after his flight touches down. But his pancreas
may continue to tick away on New York time, while his kidneys count the seconds
somewhere over the Atlantic Ocean.
Genetic
Clockwork
To study these clocks and develop a way to treat jet
lag, Eichele woke up a group of laboratory mice six hours earlier than usual --
simulating an eastward flight from Chicago to London with the flip of a light
switch. He then measured changes in their gene activity as their bodies adjusted
over the following 8-9 days.
Genes are the gears that run our internal
clocks. All of our organs possess the same ten or so "clock" genes, which govern
the production of molecules that keep time in a regular rhythm. But though the
liver, the skin, and the brain share the same genetic clockwork, they each run
on their own clock independent of the others.
In sleep-deprived mice,
some of these molecular clocks adapted more quickly than others. Those in the
pancreas -- which regulates the body's production of energy -- resisted the
change for days longer than those in kidneys, for example.
When the
molecular clocks of different organs are significantly out of synch, bodily
functions that require chemical communication can be disrupted. Eichle said that
could explain the diverse symptoms of jet lag, which range from insomnia and
depression to gastrointestinal problems. Studies have shown that the brains of
aircraft crew who experience chronic jet lag tend to shrink and make more stress
hormones, and the menstrual cycles of female flight attendants are disrupted by
regular international flights.
"We know that chronic jet lag causes
stress and impacts our health," said Kei Cho, a neuroscientist the University of
Bristol in the U.K., who discovered these effects. "This new research addresses
one of the biggest questions in biology -- how the genes are changed by
disturbances to the sleep and wake cycle."
Jet Lag Resistant
Mice
Searching for new ways to combat jet lag, Eichle examined
one of the fastest adapting clocks -- the adrenal glands. These glands are
thought to work with the brain to provide a master clock that synchronizes all
of body's clocks on a daily basis.
Using a drug that temporarily blocks
the activity of adrenal glands, Eichle and his team created a batch of jet
lag-resistant mice. A small dose administered a day before their sleepless
ordeal set their adrenal gland clocks back by an hour -- allowing their organs
to begin the process of adjusting and reducing the time it took them to adapt to
an earlier wake-up call by two or three days.
"Nobody has really ever
achieved this before," said Eichle, who published the research on June 23 in the
Journal of Clinical Investigation. "It's a first step in the right direction
towards a treatment for jet lag."
Don't expect to see this drug on the
shelf any time soon -- the U.S. Food and Drug Administration has yet to approve
a drug for jet lag, and the risks of tinkering with the body's clocks are
significant.
"Honestly, we don't know what all of these clock genes do in
the body," said Cho. "If we try to manipulate something, the side effects might
be more than we expected."
For now, the best cure for jet lag is still
the slowest: one day of rest for every time zone crossed.
- How to Beat Jet Lag: Don't Eat
- 5 Things You Must Know About Sleep
- Top 10 Mysteries of the Mind











