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From:
Meir Weiss <[log in to unmask]>
Reply To:
Cerebral Palsy List <[log in to unmask]>
Date:
Mon, 23 Oct 2006 12:35:27 -0400
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Just makes you wonder...hhhhhhmmmmmmmmmmmmmmm:)
-----Original Message-----
From: NIH news releases and news items [mailto:[log in to unmask]] On Behalf
Of NIH OLIB (NIH/OD)
Sent: Monday, October 23, 2006 11:35
To: [log in to unmask]
Subject: GENE VARIATION AFFECTS PAIN SENSITIVITY AND RISK OF CHRONIC PAIN

U.S. Department of Health and Human Services NATIONAL INSTITUTES OF HEALTH NIH
News National Institute of Neurological Disorders and Stroke (NINDS)
<http://www.ninds.nih.gov/>

EMBARGOED FOR RELEASE: Sunday, October 22, 2006, 1:00 p.m. ET 

CONTACT: Natalie Frazin or Paul Girolami, 301-496-5924, <[log in to unmask]>,
<[log in to unmask]> 

GENE VARIATION AFFECTS PAIN SENSITIVITY AND RISK OF CHRONIC PAIN Finding May
Lead to New Treatments 

A new NIH-funded study shows that a specific gene variant in humans affects both
sensitivity to short-term (acute) pain in healthy volunteers and the risk of
developing chronic pain after one kind of back surgery.  Blocking increased
activity of this gene after nerve injury or inflammation in animals prevented
development of chronic pain.


The gene in this study, "GCH1", codes for an enzyme called GTP cyclohydrolase.
The study suggests that inhibiting GTP cyclohydrolase activity might help to
prevent or treat chronic pain, which affects as many as 50 million people in the
United States.  Doctors also may be able to screen people for the gene variant
to predict their risk of chronic post-surgical pain before they undergo surgery.
The results appear in the October 22, 2006, advance online publication of
"Nature Medicine." 1

"This is a completely new pathway that contributes to the development of pain,"
says Clifford J. Woolf, M.D., of Massachusetts General Hospital and Harvard
Medical School in Boston, who led the research. "The study shows that we inherit
the extent to which we feel pain, both under normal conditions and after damage
to the nervous system."  

Dr. Woolf carried out the study in collaboration with Mitchell B. Max, M.D., of
the National Institute of Dental and Craniofacial Research
(NIDCR) in Bethesda, Maryland, and colleagues at the National Institute on
Alcoholism Abuse and Alcoholism (NIAAA) and elsewhere.  Dr. Woolf's work was
funded by the National Institute of Neurological Disorders and Stroke (NINDS).
The research team also received funding from NIDCR, NIAAA, and other
organizations.

The researchers originally identified "GCH1" by preclinical screening for genes
that undergo significant changes in expression after sciatic nerve injury.
"GCH1" is one of several genes that code for enzymes needed to produce a
chemical called tetrahydrobiopterin (BH4).  Previous studies have shown that BH4
is an essential ingredient in the process that produces dopamine and several
other nerve-signaling chemicals (neurotransmitters).  It also plays other
important roles in the body.
However, this study is the first to show that GCH1 and BH4 play a role in pain.

The investigators tested the effects of GTP cyclohydrolase and BH4 in several
animal models of pain.  They found that rats with neuropathic pain (pain caused
by nerve damage) had greatly increased levels of "GCH1" gene activity and BH4,
and that injecting a GTP cyclohydrolase inhibitor called
2,4-diamino-6-hydroxypyrimidine (DAHP) alleviated hypersensitivity to pain in
animal models of both neuropathic pain and inflammatory pain.  In contrast,
injecting BH4 greatly increased pain sensitivity.

Next, the researchers looked for "GCH1" gene variations in people.  They found
that a specific variant of the gene, identified by combinations of one-base-pair
changes in the DNA called single nucleotide polymorphisms or SNPs, protected
against development of chronic post-surgical pain in people who had participated
in a study of surgical diskectomy for back pain. About 28 percent of the people
in the surgical study had at least one copy of the pain-protective variant of
the gene (people have two copies of every gene).  The researchers found that
people with two copies of the protective version of "GCH1" had the lowest risk
of developing chronic pain, while those with just one copy had an intermediate
risk and those with no copies of the variant had the highest risk.

The researchers then found that the gene variant also appeared to reduce
sensations of acute pain in normal volunteers, who had been tested by
NIH-supported scientists Dr. William Maixner at the University of North Carolina
and Dr. Roger Fillingim at the University of Florida. Normal volunteers with two
copies of the protective gene variant were less sensitive to temporary pain
induced by pressure and other stimuli than those with one or no copies.

Analysis of blood cells from the people who had undergone back surgery showed
that, under normal conditions, the amounts of GTP cyclohydrolase and BH4 were
not significantly different in people with and without the gene variant.  When
the cells were subjected to a chemical that increases "GCH1" gene activity,
however, the amount of gene activity increased much less in people with the
pain-protective variant of the gene than it did in other people.  

The variation that affects pain sensitivity is in a region of the gene that may
control when the gene is switched on.  This, coupled with the results of the
blood study, makes the researchers suspect that the protective version of the
gene is less likely to be switched on during stressful conditions such as nerve
damage and inflammation.  "We often hear about gene mutations that are harmful,
but here is a mutation that's actually protective," says Dr. Woolf. 

The GTP cyclohydrolase inhibitor used in this study, DAHP, is not very strong
and is unlikely to be useful as a human drug, Dr. Woolf says.
Researchers are now looking for other substances that might work as GTP
cyclohydrolase inhibitor drugs in humans.

Screening people for the pain-protective gene variant could allow doctors to
identify people at high risk of developing chronic pain before they undergo
surgery, Dr. Woolf says.  Doctors might then be able to reduce the risk of
chronic pain by providing more aggressive pain relief or choosing less invasive
surgical procedures for people at high risk of chronic pain.  Several studies
have suggested that specific pain drugs or combinations of drugs can reduce the
risk of chronic pain after surgery.

Dr. Woolf and his colleagues are now planning studies to define exactly how GCH1
is switched on by nerve injury and inflammation and how it regulates pain.  They
also hope to identify other gene variants that affect pain sensitivity and the
risk of chronic pain.  "We think this gene accounts for some of the inherited
differences in pain, but other
genes may also play a role," Dr. Woolf says.    

The NINDS, NIDCR, and NIAAA are components of the National Institutes of Health
(NIH) within the Department of Health and Human Services.  The NINDS
<http://www.ninds.nih.gov> is the nation's primary supporter of biomedical
research on the brain and nervous system. The NIDCR <http://www.nidcr.nih.gov>
is the nation's leading funder of research on oral, dental, and craniofacial
health. The NIAAA <http://www.niaaa.nih.gov/> is the primary U.S. agency for
conducting and supporting research on the causes, consequences, prevention, and
treatment of alcohol abuse, alcoholism, and alcohol problems.  

"Disclosure:"  Dr. Woolf has an equity holding in a company, Solace
Pharmaceuticals., which has licensed technology from the Massachusetts General
Hospital related to this research. 

The National Institutes of Health (NIH) -- "The Nation's Medical Research
Agency" -- includes 27 Institutes and Centers and is a component of the U.S.
Department of Health and Human Services. It is the primary federal agency for
conducting and supporting basic, clinical and translational medical research,
and it investigates the causes, treatments, and cures for both common and rare
diseases. For more information about NIH and its programs, visit
<http://www.nih.gov>.
  
##

------------------------

1 Tegeder I, Costigan M, Griffin RS, Abele A, Belfer I, Schmidt H, Ehnert C,
Nejim J, Marian C, Scholz J, Wu T, Allchorne A, Diatchenko L, Binshtok AM,
Goldman D, Adolph J, Sama S, Atlas SJ, Carlezon WA, Parsegian A, Lotsch J,
Fillingim RB, Maixner W, Geisslinger G, Max MB, Woolf CJ.  "GTP cyclohydrolase
and tetrahydrobiopterin regulate pain sensitivity and persistence."  "Nature
Medicine," Advance Online Publication, October 22, 2006, doi:  10.1038/nm1490 

-------------------------

This NIH News Release is available online at:
http://www.nih.gov/news/pr/oct2006/ninds-22.htm.

-----------------------

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