A light switch for pain

From KurzweilAI:

OpsinsA team of Bio-X researchers at Stanford has developed mice whose sensitivity to pain can be dialed up or down simply by shining light on their paws. The research could help scientists understand and eventually treat chronic pain in humans. The mice in Scott Delp’s lab, unlike their human counterparts, can get pain relief from the glow of a yellow light. “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. The mice are modified with gene therapy to have pain-sensing nerves that can be controlled by light. One color of light makes the mice more sensitive to pain. Another reduces pain. 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?

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.

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