A light switch for pain

February 20, 2014

Light-sensitive proteins, or opsins, are used in a Stanford study on pain control through optogenetics (credit: Stanford University)




“This is an entirely new approach to study a huge public health issue,” Delp said. “It’s a completely new tool that is now available to neuroscientists everywhere.” He is the senior author of a research paper published Feb. 16 in Nature Biotechnology.


Increasing or decreasing the sensation of pain in these mice could help scientists understand why pain seems to continue in people after an injury has healed. Does persistent pain change those nerves in some way? And if so, how can they be changed back to a state where, in the absence of an injury, they stop sending searing messages of pain to the brain?

Optogenetics applied to the peripheral nervous system

The researchers took advantage of a technique called optogenetics, which involves light-sensitive proteins called opsins that are inserted into the nerves. Optogenetics was developed by a colleague of Delp, Karl Deisseroth, a co-author of the journal article. He has used the technique as a way of activating precise regions of the brain to better understand how the brain functions. Deisseroth is a professor of bioengineering, psychiatry and behavioral sciences.

Delp, who has an interest in muscles and movement, saw the potential for using optogenetics for studying the many nerves outside the brain. These are the nerves that control movement, pain, touch and other sensations throughout our body and that are involved in diseases like  amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s Disease.


The speed of the viral approach makes it very flexible, both for this pain work and for future studies. Researchers are developing newer forms of opsins with different properties, such as responding to different colors of light. “Because we used a viral approach we could, in the future, quickly turn around and use newer opsins,” said Montgomery, who is a Stanford Bio-X fellow.

Delp said there are many challenges to meet before results of these experiments —  either new drugs based on what they learn, or optogenetics directly — could become available to people, but that he always has that as a goal.

Delp and Deisseroth have started a company called Circuit Therapeutics to develop therapies based on optogenetics.

Abstract of Nature Biotechnology paper
