Rats with neuropathic pain that were exposed to green light-emitting diodes (LED) demonstrated more tolerance to thermal and tactile stimulus than those not bathed in the LED light, according to University of Arizona researchers.

The rats showed no side effects from the therapy, or an impaired motor or visual performance. In addition, the beneficial effects from the therapy lasted 4 days after the rats’ last exposure to the green LED light, the researchers add, in their study published recently in the journal Pain.

“Chronic pain is a serious issue afflicting millions of people of all ages,” says Mohab Ibrahim, UA assistant professor of Anesthesiology and Pharmacology and lead author of the study, in a media release from the University of Arizona. ” Opioids, while having many benefits for managing pain, come with serious side effects. While the results of the green LED are still preliminary, it holds significant promise to manage some types of chronic pain.”

In the study, the researchers placed one group of rats in clear plastic containers that were affixed with green LED strips, allowing them to be bathed in green light. Another group of rats was exposed to room light and fitted with contact lenses that allowed the green spectrum wavelength to pass through.

Both groups benefitted from the green LED exposure. However, another group of rats was fitted with opaque contact lenses, which blocked the green light from entering their visual system. These rats did not benefit from the green LED exposure, the release explains.

“While the pain-relieving qualities of green LED are clear, exactly how it works remains a puzzle,” states Rajesh Khanna, UA associate professor of Pharmacology and senior author of the study, in the release. “Early studies show that green light is increasing the levels of circulating endogenous opioids, which may explain the pain-relieving effects. Whether this will be observed in humans is not yet known and needs further work.”

The researchers are currently conducting a clinical trial using green LED light in people with fibromyalgia. Their hope is that the green light could help alleviate the participants’ pain when used alone or in combination with other treatments such as physical therapy or low-dose analgesics.

[Source(s): University of Arizona, Science Daily]