Muller A, Chabbert C. TRPV4 channels mediate the infrared laserevoked response in sensory neurons.

These results show that infrared laser radiations provide a possible way to safely stimulate retinal and vestibular ganglion neurons. A similar temperature threshold is required to trigger neurons independently of variable energy thresholds, suggesting that an absolute temperature is required.

This work focuses on the optical stimulation of dorsal root ganglion (DRG) neurons through infrared laser light stimulation. We show that a few millisecond laser pulse at 1875 nm induces a membrane depolarization, which was observed by the patch-clamp technique. This stimulation led to action potentials firing on a minority of neurons beyond an energy threshold. A depolarization without action potential was observed for the majority of DRG neurons, even beyond the action potential energy threshold. The use of ruthenium red, a thermal channel blocker, stops the action potential generation, but has no effects on membrane depolarization. Local temperature measurements reveal that the depolarization amplitude is sensitive to the amplitude of the temperature rise as well as to the time rate of change of temperature, but in a way which may not fully follow a photothermal capacitive mechanism, suggesting that more complex mechanisms are involved.

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