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Paul Candon
Medical PressCorps News Service
Placing one's hand on a hot stove or stubbing a toe in the
middle of the
night -- it seems that everyone should feel the same degree of pain and
respond in the same way.
But according to researcher Jeffrey Mogil, how much pain
a person feels is
controlled by many factors, including one's genetic makeup. Certain genes
can dictate how sensitive a person is to pain, his research shows.
Also, Mogil has found that how well pain-killing drugs work
in different
individuals can have a genetic component too. "You can give 10 people the
same dose of morphine after you've put them in presumably the same amount of
pain, and some will respond beautifully and others won't respond at all,"
he
said.
Mogil, a professor of psychology and neuroscience at the
University of
Illinois at Urbana-Champaign, will present the results of his ongoing
research into the genetics of pain February 20 at the annual meeting of the
American Association for the Advancement of Science (www.aaas.org) in
Washington, D.C.
Over the course of his 62 scientific studies on pain, Mogil
has uncovered
some basic principles. First, the more sensitive a person is to pain, the
less that person will respond to pain-killing drugs. Conversely, people less
responsive to pain benefit more from analgesics.
Second, in general, men and women tend to respond to pain
in different ways,
and different genes govern the response in each sex. "Both feel pain, but
they are responding differently, by activating different circuitry in the
brain," said Mogil.
While studying pain responses in different inbred strains
of mice, he had
found that different breeds of these animals typically have different
reactions to pain. And even within a strain of rats, there can be degrees of
variability.
However, because an inbred strain of mice has the same genetic
makeup, the
differences found within a strain are due to environmental factors like age,
stress and experience. Variations between strains of rats are due to their
genetic differences.
Mogil said he foresees three implications that his research
may have on pain
and its treatment. First, he said that knowledge about the genetics of pain
responses and their variability "should lead to a destigmatization toward
people who are pain sensitive."
Second, he said that one day a blood test may determine a
person's genetic
predisposition toward pain sensitivity. This would help therapists better
gear pain-management treatments toward individual patients.
"If a person is going in for an operation, we could
predict beforehand how
much pain they're liable to wake up in and how well they're going to respond
to the codeine they'll be given after surgery," Mogil explained. "If
they're
going to wake up in a lot of pain and respond poorly to the codeine, then we
can up the dose or switch to more powerful analgesics. If we predict they
won't be in much pain and will respond perfectly well to the codeine, then
we can give a low dose and cut down on side effects."
Third, in the future, gene therapy may be able to provide
people with
chronic pain a way to better cope with their condition.
Mogil has also published a review paper detailing current
scientific trends
and theories on pain in the Proceedings of the National Academy of Sciences
(1999;96:7744-7751).
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