People who say they are less sensitive to pain than others could be right. Researchers said on Monday they had found a gene that appears to affect how people feel discomfort.
Tests in rats showed that blocking increased activity of the gene after nerve injury or inflammation could prevent the development of chronic pain, a finding that points to possible ways to develop new pain drugs.
And studies in volunteers showed that about a quarter of them had the genetic variant that protects them from pain somewhat, and 3 percent carried two mutated copies that make them exceptionally insensitive to pain, the researchers reported in the journal Nature Medicine.
“This is a completely new pathway that contributes to the development of pain,” said Dr. Clifford Woolf 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.”
An estimated 40 million people in the United States alone, or nearly 1 in 5 adults, suffer from chronic pain.
The affected gene is called GCH1, which codes for an enzyme called GTP cyclohydrolase. This enzyme in turn is needed to produce a chemical called tetrahydrobiopterin or BH4.
“Our results tell us that BH4 is a key pain-producing molecule — when it goes up, patients experience pain, and if it is not elevated, they will have less pain,” Woolf said in a statement.
“The data also suggest that individuals who say they feel less pain are not just stoics but genuinely have inherited a molecular machinery that reduces their perception of pain. This difference results not from personality or culture, but real differences in the biology of the sensory nervous system.”
Woolf and researchers in Germany and at the U.S. National Institutes of Health said that rats with pain caused by nerve damage had higher levels of GCH1 gene activity and of BH4.
When they injected a drug that interferes with GTP cyclohydrolase, the enzyme controlled by the gene, the rats seemed less sensitive to the pain. Injecting BH4 greatly increased pain sensitivity, they found.
The researchers tested 400 healthy people and found that volunteers with two copies of the protective gene variant were less sensitive to pain in tests.
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 drug used in the study, DAHP, is not very strong and is unlikely to be useful as a human medication, said Woolf, who owns stock in a company called Solace Pharmaceuticals, which has licensed the findings for potential drug development.
|copyright © 2006 Reuters. All rights reserved.|