Activation of Transient Receptor Potential Vanilloid-3 Channels in Keratinocytes Induces Pruritus in Humans
Jin Cheol Kim, Han Bi Kim, Won-Sik Shim, In Suk Kwak, Bo Young Chung, Seok Young Kang, Chun Wook Park, Hye One Kim
Carvacrol, a natural transient receptor potential vanilloid-3 activator, has been reported to cause pruritus in mice. This study aimed to evaluate the effects of carvacrol and various antipruritic agents in humans. A stimulation test with carvacrol, β-alanine, and histamine was performed. After application of the pruritic solutions, the skin was stimulated with pinpricks. In inhibition test A, Forsythia suspensa extract, containing forsythoside B (a transient receptor potential vanilloid-3 inhibitor), was applied by pricking prior to stimulation with pruritogens. In inhibition test B, olopatadine solution, tacrolimus ointment, and Scutellaria baicalensis root extract were applied, and carvacrol was applied to the same region. Carvacrol induces moderate pruritus in humans. The pruritus was relieved by Forsythia suspensa extract and olopatadine solution after 20 min of application and by tacrolimus ointment and Scutellaria baicalenis extract after 24 h of application. These results suggest that carvacrol is a pruritogen in humans, and that carvacrol-induced pruritus is inhibited by various antipruritic agents.
Pruritus is a distressing sensation that triggers a desire to scratch and has a significant impact on quality of life. Current evidence strongly suggests that transient receptor potential ion channels in human skin play a key role in many types of pruritus. This study examined the putative effect of transient receptor potential vanilloid-3 channel activation on pruritus. The effect was measured by comparing the subjective degree of pruritus with that of other pruritogens. The results suggest that transient receptor potential vanilloid-3 activation is a potential pruritogen, and novel treatment modalities can be suggested by inhibiting this channel.