Comparison of pruritus and sensory qualities induced by capsaicin, histamine and cowhage

Abstract

Background In skin diseases and experimental models of pruritus, pure itch is accompanied by additional sensations that are poorly characterized. Objectives This study compared the sensory qualities evoked by different models of experimentally induced pruritus including skin prick testing (SPT) with histamine or capsaicin and application of cowhage spicules. SPT as a method of capsaicin application was validated for this purpose. Methods Two pilot experiments were performed in eight healthy volunteers. First, a concentration of 8% capsaicin was identified as evoking a reproducible itch using SPT. Further, a list of the seven most frequently reported sensations was chosen after SPT with 10 mg/mL histamine, 8% capsaicin and application of 40–45 cowhage spicules. Finally, 31 subjects were challenged with the same itch‐inducers. Wheal and flare were measured at 10, 20, 40, 60 and 90 min, itch intensity every minute for 30 min, and the overall evaluation of sensory descriptors were recorded on a 100‐mm visual analogue scale once itching had subsided. Results Skin prick testing with histamine and capsaicin resulted in flare reactions, which were 23% smaller for capsaicin (P < 0.001). Histamine, capsaicin and cowhage‐induced pruritus, the duration of which was shorter for cowhage than for histamine (13.5 ± 1.4 vs. 8.8 ± 1.2 min, P = 0.005). Different mediators induced sensations of different intensities. Capsaicin produced less itch and physical urge to scratch than histamine (P = 0.001) and cowhage (P < 0.001). However, both capsaicin and cowhage induced more burning than histamine (P = 0.002 and P = 0.04, respectively). Provocation with cowhage caused more intense sensations of pricking than histamine (P = 0.033). Conclusion This study shows that provocation with histamine, capsaicin and cowhage results in itch responses that are different in their duration, the profile of accompanying sensations, and the flare that comes with the itch.

A visual analogue scale for itch and pain in 23 cases of cholinergic urticaria

“…Hawro and colleagues stated that different pruritic inducers evoke different and unique sensory qualities. 12 Our main study limitation was exclusion of follicular-type CholU with a positive ASST result.…”

Itch induction by audiovisual stimuli and histamine iontophoresis: a randomized, controlled noninferiority study

“…So far, there have been studies comparing the effectiveness of different substance‐dependent itch‐inducing methods . However, no study thus far has compared mental induction to substance‐dependent methods.…”

“…As there have been no studies describing the quality of audiovisually‐induced itch and only a few describing the quality of itch induced by histamine, a secondary aim was to assess the quality and location of induced itch.…”

Mas-related G protein–coupled receptor X2 and its activators in dermatologic allergies

“…162 Mucunain also activates PAR2 and PAR4. When mucunain is applied intradermally with use of cowhage spicules, it induces strong itch but does not cause a wheal, 163,164 although it has been reported to degranulate LAD2 MCs in vitro. 6,24,162 In patients with AD, mucunain causes increased itch sensations, stronger hyperkinesis, 165 and prolonged itch duration compared with in HCs.…”