WASHINGTON, Feb. 20 (UPI) -- Male and female mice experience pain differently
and that could help to understand why some people feel pain to a stimulus, while
others have almost no pain at all.
"We know that there are differences between men and women in how they experience
pain and how they respond to pain medication," said Jeffrey Mogil, professor of
psychology and neuroscience at the University of Illinois Urbana-Champaign.
Women seem to be more sensitive to pain, he said, and also seem to have less
response to painkilling drugs -- analgesics.
But in Mogil's new studies on mice, he has found that male and female mice
process pain through different nervous system pathways. At the annual meeting of
the American Association for the Advancement of Science in Washington on Sunday,
Mogil said that if male mice are given a specific drug, it blocks the affects of
certain painkillers. The drug has no effect on female mice. He has demonstrated
a similar difference in rats.
Mogil said that if the differences persist throughout mammals such differences
might be found in men and women.
"The sexual difference in perceiving pain are small -- about a 5 to 10 percent
difference," Mogil said, "but the exciting part of this research is
understanding how pain is produced in each sex. It may be possible to produce
analgesics that produce pain relief in one sex and not the other."
He is also trying to pinpoint which genes control perception of pain so we can
"answer the question as to why don't we all experience pain in the same way."
Mogil said that because these differences seem to be genetic it could reduce the
stigma attached to some people who seem more sensitive to pain that others.
Mogil said his studies have located the general area of where those genetic
clues are hidden. But, he said, using the analogy of the United States as the
pain gene, that clue is buried in some house, on some block in some city in
Iowa. It is going to take time to track it down, he said.
Researchers said that headway is being made in getting to the basic
understanding of pain so, that pain-relief products can be developed that
eliminate inappropriate pain without causing inappropriate side effects.
Allan Basbaum, professor and chairman of the department of anatomy at the
University of California, San Francisco, said persistent pain -- a condition
caused by injury to nerves that exists after healing has occurred -- should be
considered a disease in itself.
He said genetic understanding of pain "has created numbers of new therapeutic
targets for analgesic drugs. Because these are unique target, drugs aimed at
these targets could lead to treatment without side effects."
For example, Basbaum said acute pain -- that which tells a man with a broken leg
not to walk on it -- differs from chronic pain caused by nerve damage, and the
types of pain are governed by different molecular signals.
In another study presented at the meeting, Dr. Catherine Bushnell, professor of
anesthesia at McGill University, Montreal, demonstrated that using distraction
methods one can change the amount of pain register in the brain.
She used two common imaging procedures, positron emission tomography (PET) and
magnetic resonance imaging (MRI) to actually look at differences in brain
activity when subjects thrust their hands into painfully hot water and then were
asked to use hypnotic suggestions to increase or decrease pain sensation.
Similarly, distraction techniques -- asking the subjects to perform other mental
tasks while submitting to the stimulus -- also produced changes in brain
activity.
"There appears to be a basis for the observation that psychological state can
alter how much pain we feel," Bushnell said.
(c) 2000 UPI All rights reserved.
Copyright 2000 by United Press International.
