June 4 (HealthDay News) -- Animal studies suggest that gene therapy might block tough-to-treat neuropathic pain.

Neuropathic pain -- a type of chronic pain in people for which there are few effective treatments -- is the result of injury- or disease-related damage to nerve fibers. Even after surrounding tissue has healed, the damaged nerve fibers continue to send pain signals to the brain, according to background information in the article.

For some people, neuropathic pain causes long-term disability and dependence on pain medications.

In this study with rats, researchers at the University of Pittsburgh introduced the gene for part of the human glycine receptor (GlyR). This gene is found primarily on the surface of nerve cells in the spinal cord and the lower brain but not in the nerves in the limbs.

The researchers used an engineered herpes simplex virus (HSV) to deliver the gene into the paws of some rats, while other rats received only the HSV vector without the inserted gene. All the rats were then injected with an irritant that simulated symptoms of neuropathic pain, followed by injections of glycine to activate the GlyR receptor.

The glycine injection halted pain response in GlyR-HSV-treated rats but not in the rats that received only the HSV vector.

The findings suggest that targeted use of GlyR-HSV and activation with glycine may help treat humans with neuropathic pain and other chronic pain disorders, the study authors said.

The study was presented at the annual meeting of the American Society of Gene Therapy, in Seattle.