Fw: Study Confirms Brain's Natural Painkiller System

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From: " Martha Munch (by way of ilena rose) " <MartyDavMun@...>

Sent: Wednesday, July 25, 2001 10:32 AM

Subject: Study Confirms Brain's Natural Painkiller System

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Study Confirms Brain's Natural Painkiller System

ImmuneSupport.com

07-25-2001

A unique experiment that studied chemical activity in the brains of human

volunteers while they experienced sustained pain is providing new insight

into the importance of the body's natural painkiller system and why each of

us experiences pain differently. The results were published in the July 13

issue of Science magazine.

The study results confirm long-suspected connections between pain-dampening

changes in brain chemistry, and the senses and emotions experienced by

people in pain. The findings may help researchers better understand

prolonged pain and find more effective ways to treat the chronic pain of

several conditions, including fibromyalgia and chronic fatigue syndrome.

" This result gives us new appreciation for the power of our brain's own

anti-pain system, and shows how brain chemistry regulates sensory and

emotional experiences, " said lead author Jon-Kar Zubieta, M.D., Ph.D.,

assistant professor of psychiatry and radiology at the U-M Medical School,

and assistant research scientist in the Mental Health Research Institute.

The double-blind, placebo-controlled, brain imaging study, was conducted by

researchers from the University of Michigan Health System and School of

Dentistry. It is the first to combine sustained induced pain with

simultaneous brain-scan monitoring of a key neurochemical system, and the

self-reported pain ratings of human participants.

The research cements the critical role of the mu opioid system, in which

naturally produced chemicals called endogenous opioids, or endorphins,

match up with receptors on the surface of brain cells and reduce or block

the spread of pain messages from the body through the brain.

The body-brain pain connection occurs on many levels. As our bodies respond

to the sensation of pain, our brains integrate that sensation with our

knowledge of the environment in which it occurs. Then the brain produces

the endogenous opiods that lessen our perception of painful nerve signals,

protecting us from fully feeling them. The way the chemicals produce this

effect is similar to the action of some pain medications.

The study found that the onset and slow increase of jaw muscle pain over 20

minutes caused a surge in the release of the chemicals, and that the flood

of those chemicals coincided with a reduction in the amount of pain and

pain-related emotions the volunteers said they felt.

Instead of looking at the general activity of the brain, the researchers

set out to watch the response of the chemical systems involved in

suppressing the experience of pain - namely, the opioid system - and to

relate its function to the volunteers' subjective reports of what they

felt.

The researchers chose first to study prolonged jaw pain, mimicking the

chronic condition called temporo-mandibular joint disorder. To simulate

TMJ's symptoms, they injected high-concentration salt water directly into

each volunteer's jaw muscle, causing a painful sensation that continued

only as long as the water was injected. A placebo solution that does not

cause pain was also used for comparison.

The regions most significantly affected were exactly those involved in the

affective, or emotional, responses, and those primarily involved in

processing sensations.

The activation of the anti-pain response was dramatic in some volunteers

when the placebo and pain-inducing conditions were compared, while in

others the response was much less pronounced. And those who had the biggest

change tended to rate the experience of pain, both in its sensory and

emotional aspects, the lowest.

" This may help explain why some people are more sensitive, or less

sensitive, than others when it comes to painful sensations, " Zubieta said.

" We show that people vary both in the number of receptors that they have

for these anti-pain brain chemicals, and in their ability to release the

anti-pain chemicals themselves. Both of these factors appear to determine

the emotional and sensory aspects of a painful experience. "

" Such variability in the pain-response system may help explain why some

people react to pain and pain medications differently. It may also be quite

relevant to why some people, but not others, develop chronic pain

conditions. " Zubieta said.

The researchers now hope their findings will lead to more understanding of

chronic pain and ways to treat it. Also important is the information

gathered on variation among individuals' pain response, which may help

clinicians tailor treatment or learn why certain chronic pain conditions

such as fibromyalgia are more common in women.