Neuroscientists Find Way To Control Pain With Light
Gail Dufault, the Transitional Healthcare Coordinator at the Barnstable County House of Corrections, prepares a dose of Vivitrol at the prison in Buzzards Bay, Massachusetts September 2, 2014. Barnstable is believed to be the first jail in the country to launch an intensive voluntary recovery program for opiate-addicted inmates with the use of Vivitrol, an injectable non-narcotic drug that blocks receptors in the brain and bars addicts from getting high off heroin and other opioids for about 25 days, at a cost of about $1,000 a shot. Picture taken September 2, 2014. REUTERS

Researchers from Washington University School of Medicine in St Louis have found a new way that can activate the opioid receptors with light, instead of painkillers. The study findings are published online in the journal Neuron, which indicates a new line of discovery that also could lead to better pain-killing drugs with fewer side effects.

Opioid receptors are G-proteins that are widely distributed in our brain and are also found in spinal cord as well the digestive system and have been targeted for the treatment of pain and related disorders for thousands of years. They also are involved in breathing and play a role in the reward response.

The painkillers or the opioid drugs which target the opioid receptors in the brain have been the best option for patients suffering from severe pain since long time, despite the abuse potential of them. But with this latest development might form a new path as a treatment for pain relief without the addictive properties and side effects posed by opiates.

The scientists melded the light-sensing protein rhodopsin to key parts of opioid receptors to activate receptor pathways using light in a test tube with an aim to check the effect of light. By doing so, they were able to build a receptor that responds to light in exactly the same way that standard opioid receptors respond to pain-killing drugs. They also found that by injecting these receptors into the mice brain, their behaviour was influenced in a similar way to that of drugs.

First author Edward R. Siuda, a graduate student in the laboratory of Michael R. Bruchas, and an assistant professor of anesthesiology and of neurobiology, says, "It's conceivable that with much more research we could develop ways to use light to relieve pain without a patient needing to take a pain-killing drug with side effects"

The study’s principal investigator Michael R. Bruchas has said that working with light rather than pain-killing drugs provides a better platform to understand the functioning of the receptors within the complex array of cells and circuits in the brain and spinal cord.

Bruchas further explained that "By activating the receptors with light, we are presumably causing the brain to release more dopamine. Rather than a drug such as morphine activating an opioid receptor, the light provides the reward."

Opioid painkillers such as Vicodin or OxyContin do relieve pain but when consumed for a longer period of time, the patients develop tolerance to them and even sometimes lead to addiction. They can slow down a person's breathing and can also cause constipation.

The team is now planning to carry out future studies that will use these receptors to test ways to control the brain cells that mediate pain and reward behaviour with light rather than drugs.

To contact the writer, email:ruchira.dhoke@gmail.com

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