[HTML][HTML] TRPV1 activity and substance P release are required for corneal cold nociception

F Li, W Yang, H Jiang, C Guo, AJW Huang, H Hu… - Nature …, 2019 - nature.com
F Li, W Yang, H Jiang, C Guo, AJW Huang, H Hu, Q Liu
Nature communications, 2019nature.com
As a protective mechanism, the cornea is sensitive to noxious stimuli. Here, we show that in
mice, a high proportion of corneal TRPM8+ cold-sensing fibers express the heat-sensitive
TRPV1 channel. Despite its insensitivity to cold, TRPV1 enhances membrane potential
changes and electrical firing of TRPM8+ neurons in response to cold stimulation. This
elevated neuronal excitability leads to augmented ocular cold nociception in mice. In a
model of dry eye disease, the expression of TRPV1 in TRPM8+ cold-sensing fibers is …
Abstract
As a protective mechanism, the cornea is sensitive to noxious stimuli. Here, we show that in mice, a high proportion of corneal TRPM8+ cold-sensing fibers express the heat-sensitive TRPV1 channel. Despite its insensitivity to cold, TRPV1 enhances membrane potential changes and electrical firing of TRPM8+ neurons in response to cold stimulation. This elevated neuronal excitability leads to augmented ocular cold nociception in mice. In a model of dry eye disease, the expression of TRPV1 in TRPM8+ cold-sensing fibers is increased, and results in severe cold allodynia. Overexpression of TRPV1 in TRPM8+ sensory neurons leads to cold allodynia in both corneal and non-corneal tissues without affecting their thermal sensitivity. TRPV1-dependent neuronal sensitization facilitates the release of the neuropeptide substance P from TRPM8+ cold-sensing neurons to signal nociception in response to cold. Our study identifies a mechanism underlying corneal cold nociception and suggests a potential target for the treatment of ocular pain.
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