Topically applied camphor elicits a sensation of cool, but nothing is known about how it affects cold temperature sensing. We found that camphor sensitizes a subpopulation of menthol-sensitive native cutaneous nociceptors in the mouse to cold, but desensitizes and partially blocks heterologously expressed TRPM8 (transient receptor potential cation channel subfamily M member 8). In contrast, camphor reduces potassium outward currents in cultured sensory neurons and, in cold nociceptors, the cold-sensitizing effects of camphor and menthol are additive. Using a membrane potential dye-based screening assay and heterologously expressed potassium channels, we found that the effects of camphor are mediated by inhibition of Kv7.2/3 channels subtypes that generate the M-current in neurons. In line with this finding, the specific M-current blocker XE991 reproduced the cold-sensitizing effect of camphor in nociceptors. However, the M-channel blocking effects of XE991 and camphor are not sufficient to initiate cold transduction but require a cold-activated inward current generated by TRPM8. The cold-sensitizing effects of XE991 and camphor are largest in high-threshold cold nociceptors. Low-threshold corneal cold thermoreceptors that express high levels of TRPM8 and lack potassium channels are not affected by camphor. We also found that menthol--like camphor--potently inhibits Kv7.2/3 channels. The apparent functional synergism arising from TRPM8 activation and M-current block can improve the effectiveness of topical coolants and cooling lotions, and may also enhance TRPM8-mediated analgesia.

• MeSH
• kafr farmakologie   MeSH
• kationtové kanály TRPM genetika   metabolismus   MeSH
• menthol farmakologie   MeSH
• myši inbrední C57BL MeSH
• myši MeSH
• nervová vlákna nemyelinizovaná účinky léků   metabolismus   MeSH
• nízká teplota MeSH
• nociceptory metabolismus   fyziologie   MeSH
• signální transdukce účinky léků   fyziologie   MeSH
• spinální ganglia účinky léků   metabolismus   MeSH
• termoreceptory metabolismus   fyziologie   MeSH
• vnímání teploty účinky léků   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• kafr MeSH
• kationtové kanály TRPM MeSH
• menthol MeSH
• TRPM8 protein, mouse MeSH Prohlížeč