Medical

Stanford scientists use light to control pain in mice

Stanford scientists use light to control pain in mice
Researchers have shown that that exposure to one color of light can increase pain sensitivity in genetically modified mice, whilst another reduces it (Image: Shutterstock)
Researchers have shown that that exposure to one color of light can increase pain sensitivity in genetically modified mice, whilst another reduces it (Image: Shutterstock)
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The ability to modify pain sensitivity is based on the use of light-sensitive proteins, or opsins
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The ability to modify pain sensitivity is based on the use of light-sensitive proteins, or opsins
Researchers have shown that that exposure to one color of light can increase pain sensitivity in genetically modified mice, whilst another reduces it (Image: Shutterstock)
2/2
Researchers have shown that that exposure to one color of light can increase pain sensitivity in genetically modified mice, whilst another reduces it (Image: Shutterstock)

Scientists at Stanford Bio-X, the institution's department for breakthrough discoveries about the human body and disease, have modified mice with gene therapy so that their sensitivity to pain can be altered by shining light on their paws.

This application of the neuromodulation technique called optogenetics starts with the insertion of light-sensitive proteins called opsins into the nerves of the mice. The researchers then showed that that exposure to one color of light can increase pain sensitivity in the mice whilst another reduces it.

The research is helping to develop a better understanding of what pain is and why it occurs. It is also hoped that it will provide some clues as to why some people feel pain more or less than others and the extent to which light might ultimately be able to treat pain in humans, in particularly those living with chronic and debilitating pain conditions.

The ability to modify pain sensitivity is based on the use of light-sensitive proteins, or opsins
The ability to modify pain sensitivity is based on the use of light-sensitive proteins, or opsins

The mice were modified by injecting a virus directly into their nerves that had been engineered to contain opsin-producing DNA. After a few weeks it was found that only the nerves that control pain had taken on the opsin proteins. As a result, the nerves were either more or less likely to fire depending on the color of light to which they were exposed.

"This powerful approach shows great potential for helping the millions who suffer pain from nerve damage," said Linda Porter, the pain policy adviser at the National Institute of Neurological Disorders and Stroke and a leader of the NIH's Pain Consortium. "Now, with a flick of a switch, scientists may be able to rapidly test new pain relieving medications and, one day, doctors may be able to use light to relieve pain."

Different opsins are now being produced that will react differently to different colors of light and the use of viruses to deliver the opsins means that they can be tested very quickly.

"Because we used a viral approach we could, in the future, quickly turn around and use newer opsins," says study leader Kate Montgomery in a press release.

Optogenetics was developed as a means of activating precise regions of the brain to better understand its functions. During a previous piece of research in which optogenetics was being used to control nerves that excite muscles, it was found that the opsins would on occasion be accidentally placed into the nerves that signal pain. It was this occurrence that triggered the research into the control of pain sensitivity.

Source: Stanford University

5 comments
5 comments
Nairda
Nice. One step closer to super soldiers that don't feel pain or emotion.
Slowburn
@ Nairda People that do not feel pain die an early death because pain is the warning system that something is wrong. Not feeling emotions make for louse soldiers because it is love that motivates good soldiers and empathy that keeps them from committing the crimes that are the surest way to lose a war. This is why the anti-western civilization press makes sure that the crimes committed by the western militarizes receive headlines for as long as possible and the many more crimes by our enemies are hushed up or explained away.
gerald
I wonder is any of the scientists at Stanford Bio-X ever gave a moment's thought to the fact that maybe they have no moral or ethical right to submit any animal to pain, whether physically invasive or not...?
Ralf Biernacki
At the research stage, they are using opsins, because they allow controlled switching on and off of the effect. Eventually the same viral vector could be used to deliver modifications that simply reduce the intensity of pain without the need for external optical stimulation.

@Max Andreozzi: One day, you will be in pain. I know you will then refrain from using animal-tested medicines, because you are not a hypocrite, and are using emotion-charged words like "torture" with a thorough knowledge of what you are talking about.

And for all those ignorant and appalled: nowadays pain is generally induced in animal testing in the same way it is induced in human volunteer testing, either by immersion of extremities in ice water or by pricking with an injection needle to induce a cringe reflex. It's not worse than what three-year-old children endure when being vaccinated. Yes, it used to be much worse in the bad old days, in both animal and human research. But not anymore. Keep up.