# Light-induced analgesia provides a drug-free optical method for pain relief via activation of TRAAK k+ channels

## TL;DR

A new drug-free method for pain relief in animals uses light to activate potassium channels, offering a non-invasive alternative to traditional pain management.

## Contribution

The study introduces light-induced analgesia, a novel, non-invasive, and drug-free approach to pain relief via TRAAK channel activation.

## Key findings

- 365 nm light activates TRAAK potassium channels by oxidizing a methionine residue, inducing a conformational change.
- Light-induced analgesia silences nociceptors and provides potent, long-lasting pain relief in rodents.
- The mechanism can be transferred to other K2P channels via a single-point mutation, making them light-sensitive.

## Abstract

Pain management in animal experimentation is crucial for both ethical and scientific reasons, as unmanaged pain can distort physiological responses compromising data reliability. Current strategies are often invasive and pharmacology-based, introducing variability and confounding effects. Here, we present Light-Induced Analgesia, a drug-free, non-invasive method for pain relief in animals. We show that 365 nm illumination activates the pain-inhibitory TRAAK two-pore domain potassium (K2P) channel. This activation is driven by the oxidation of a native methionine at TRAAK’s regulatory fenestration site, triggering a conformational switch from its inactive (down) to active (up) state. We further demonstrate that this mechanism can be transferred to other related K2Ps via a single-point mutation, rendering them light-sensitive. In rodents, gentle skin exposure to 365 nm is sufficient to activate endogenous TRAAK, silence nociceptors, and produce potent, long-lasting analgesia that outperforms standard treatments. Light-Induced Analgesia thus offers an effective, drug-free alternative that can enhance animal welfare and experimental reliability in preclinical research.

Membrane ion channels can be responsive to a variety of stimuli such as pressure, temperature, or pH. Here, the authors show that simply shining 365 nm light activates a native potassium channel in rodent pain-sensing neurons, delivering powerful analgesia without drugs or genetic manipulations.