Max
08-18-2003, 11:13 AM
Study sheds light on pathways of pain
Injuries can result in neurological re-wiring that sends pain signals at the lightest touch on the skin
Mike Fuhrmann
Canadian Press
Researchers have found a receptor site for pain, but no drugs to block it.
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TORONTO -- The pain is chronic and intense, and can be brought on by the most innocuous event -- like putting on a shirt.
For its sufferers, neuropathic pain is a nightmare that won't go away.
It can result from injury in a motorcycle accident, a mishap during surgery or from common diseases including diabetes and cancer.
A new study sheds light on the process by which nerve signals can become scrambled, leading the human body to feel such pain.
Researchers at the Hospital for Sick Children and the National Institute of Health Sciences in Japan have identified a key culprit: A molecule known as a P2X4 receptor that exists on the surface of cells in the spinal cord.
Their study is published in the current issue of Nature.
In the case of normal "good" pain resulting from, say, stepping on a tack, the pain goes away after the tissue damage is repaired, explains study co-author Dr. Michael Salter, director of the University of Toronto Centre for the Study of Pain.
"Neuropathic pain is very different from that," he says. It typically occurs when there has been damage to peripheral nerves, which extend from the spinal cord all the way to fingertips and toes and other body surfaces.
That damage can lead to a "rewiring" of cells inside the spinal cord such that a light touch on the surface of the body ends up being transmitted to the brain as a pain signal. Or what may also occur is an amplification of the signal in the spinal cord, with the same result.
"In that situation the nervous system is abnormal, it's not normally wired up," Salter says. "And then the changes that occur can be very profound."
Even the light touch of clothing can be intensely painful. Such pain is also highly resistant to strong narcotics like morphine or heroin.
"Neuropathic pain can be highly debilitating. It can destroy people's lives," says Salter, adding that it affects millions of people worldwide.
Using rats and a variety of blocking drugs, the researchers were able to pinpoint the role of the P2X4 receptor in transmitting neuropathic pain.
However, there is no single drug that blocks just that receptor, and Salter says he is now working hard to find such a drug. Drugs that block several receptors are liable to have unwanted side-effects, he noted.
"We're at the very early stages with this," said Salter, estimating that a specific drug to block the P2X4 receptor might realistically be available to patients in five to 10 years.
© Copyright 2003 Vancouver Sun
http://www.canada.com/health/story.html?id=4D3EAB41-9D5B-4D3B-BB08-08D93D0FF93E
Injuries can result in neurological re-wiring that sends pain signals at the lightest touch on the skin
Mike Fuhrmann
Canadian Press
Researchers have found a receptor site for pain, but no drugs to block it.
ADVERTISEMENT
TORONTO -- The pain is chronic and intense, and can be brought on by the most innocuous event -- like putting on a shirt.
For its sufferers, neuropathic pain is a nightmare that won't go away.
It can result from injury in a motorcycle accident, a mishap during surgery or from common diseases including diabetes and cancer.
A new study sheds light on the process by which nerve signals can become scrambled, leading the human body to feel such pain.
Researchers at the Hospital for Sick Children and the National Institute of Health Sciences in Japan have identified a key culprit: A molecule known as a P2X4 receptor that exists on the surface of cells in the spinal cord.
Their study is published in the current issue of Nature.
In the case of normal "good" pain resulting from, say, stepping on a tack, the pain goes away after the tissue damage is repaired, explains study co-author Dr. Michael Salter, director of the University of Toronto Centre for the Study of Pain.
"Neuropathic pain is very different from that," he says. It typically occurs when there has been damage to peripheral nerves, which extend from the spinal cord all the way to fingertips and toes and other body surfaces.
That damage can lead to a "rewiring" of cells inside the spinal cord such that a light touch on the surface of the body ends up being transmitted to the brain as a pain signal. Or what may also occur is an amplification of the signal in the spinal cord, with the same result.
"In that situation the nervous system is abnormal, it's not normally wired up," Salter says. "And then the changes that occur can be very profound."
Even the light touch of clothing can be intensely painful. Such pain is also highly resistant to strong narcotics like morphine or heroin.
"Neuropathic pain can be highly debilitating. It can destroy people's lives," says Salter, adding that it affects millions of people worldwide.
Using rats and a variety of blocking drugs, the researchers were able to pinpoint the role of the P2X4 receptor in transmitting neuropathic pain.
However, there is no single drug that blocks just that receptor, and Salter says he is now working hard to find such a drug. Drugs that block several receptors are liable to have unwanted side-effects, he noted.
"We're at the very early stages with this," said Salter, estimating that a specific drug to block the P2X4 receptor might realistically be available to patients in five to 10 years.
© Copyright 2003 Vancouver Sun
http://www.canada.com/health/story.html?id=4D3EAB41-9D5B-4D3B-BB08-08D93D0FF93E