A Human Surrogate Model of Itch Utilizing the TRPA1 Agonist Trans-cinnamaldehyde

• Published in: Acta dermato-venereologica Vol. 95; no. 7; p. 798
• Main Authors: Højland, C, Andersen, H, Poulsen, J, Arendt-Nielsen, L, Gazerani, P
• Format: Journal Article
• Language: English
• Published: Sweden 01.09.2015
• Subjects: Acrolein - administration & dosage; Acrolein - analogs & derivatives; Administration, Cutaneous; Calcium Channels - metabolism; Feasibility Studies; Female; Healthy Volunteers; Humans; Irritants - administration & dosage; Male; Nerve Tissue Proteins - agonists; Nerve Tissue Proteins - metabolism; Pruritus - chemically induced; Pruritus - diagnosis; Pruritus - metabolism; Pruritus - physiopathology; Regional Blood Flow; Severity of Illness Index; Skin - blood supply; Skin - drug effects; Skin - metabolism; Skin - pathology; Skin - physiopathology; Skin Temperature; Time Factors; Transient Receptor Potential Channels - agonists; Transient Receptor Potential Channels - metabolism; TRPA1 Cation Channel; Young Adult
• ISSN: 0001-5555; 1651-2057; 1651-2057
• DOI: 10.2340/00015555-2103

The thermoreceptive transient receptor potential ankyrin 1 (TRPA1) is important in the transmission of itch, and its agonist trans-cinnamaldehyde has occasionally been reported to be a pruritogen in humans. However, no studies have accurately quantified the capabilities of trans-cinnamaldehyde to induce itch and related dysesthetic sensations. The present study examined alterations in somatosensory and vasomotor parameters in response to topical trans-cinnamaldehyde 5% and vehicle (ethanol) in 24 healthy subjects. During the study the following parameters were recorded: itch area and intensity, hyperknesis, alloknesis, neurogenic flare, skin blood flow and temperature. Trans-cinnamaldehyde evoked moderate itch sensation, flare, hyperknesis and alloknesis (p < 0.001). Blood flow and skin temperature were elevated in the area of trans-cinnamaldehyde application (p < 0.001). Significant positive correlations were found between blood flow and skin temperature, itch area and blood flow, and itch area and skin temperature. Topical trans-cinnamaldehyde proved feasible as a human itch model with applicability in studying itch mechanisms or anti-pruritic drug profiling.