Washington: Researchers have discovered a gene that is linked to chronic pain - a finding that could open the door to better pain medications.
University of Cambridge researchers have isolated a gene called HCN2, which produces a protein that causes chronic pain.
Chronic pain comes in two main varieties, the first, inflammatory pain, occurs when a persistent injury (e.g. a burn or arthritis) results in an enhanced sensitivity of pain-sensitive nerve endings, thus increasing the sensation of pain.
More obdurate is the second variety of chronic pain, neuropathic pain, in which nerve damage causes on-going pain and a hypersensitivity to stimuli and is also a common component of lower back pain and other chronic painful conditions.
Neuropathic pain, which is often lifelong, is a surprisingly common condition and is poorly treated by current drugs. Neuropathic pain is seen in patients with diabetes (affecting 3.7m patients in Europe, USA and Japan) and as a painful after-effect of shingles, as well as often being a consequence of cancer chemotherapy.
“Individuals suffering from neuropathic pain often have little or no respite because of the lack of effective medications. Our research lays the groundwork for the development of new drugs to treat chronic pain by blocking HCN2,” said lead researcher Professor Peter McNaughton, Head of the Department of Pharmacology at the University of Cambridge, said.
The researchers engineered the removal of the HCN2 gene from pain-sensitive nerves and then carried out studies using electrical stimuli on these nerves in cell cultures to determine how their properties were altered by the removal of HCN2.
Following promising results from the in vitro studies in cell cultures, the researchers studied genetically modified mice in which the HCN2 gene had been deleted.
By measuring the speed with which the mice withdrew from different types of painful stimuli, the scientists were able to determine that deleting the HCN2 gene abolished neuropathic pain.
Interestingly, researchers also found that deleting HCN2 does not affect normal acute pain (the type of pain produced by a sudden injury– such as biting one``s tongue).
The study is published in the journal Science.