Pruritic and Vascular Responses Induced by Serotonin in Patients with Atopic Dermatitis and in Healthy Controls

Pruritic and Vascular Responses Induced by Serotonin in Patients with Atopic Dermatitis and in Healthy Controls

doi: 10.2340/00015555-1473

Authors:

Aram Rausl, Klas Nordlind, Carl-Fredrik Wahlgren
Dermatology and Venereology Unit, Department of Medicine, Solna, Karolinska University Hospital, Karolinska Institutet, SE-171 76 Stockholm, Sweden. E-mail: aram.rasul@ki.se

Abstract:

Atopic dermatitis (AD) is a chronic inflammatory skin disease with often severe itch. The aim of this study was to determine the pruritogenic and vascular effect of serotonin (5-hydroxytryptamine; 5-HT) in patients with AD and in healthy controls. A 50 µg dose of 5-HT was injected intradermally into non-lesional skin of 25 patients with AD and 25 healthy control individuals, and the effect compared with 0.2 µg histamine as a positive control, and buffer as a negative control. Pruritus was recorded by the subjects, using a computerized visual analogue scale, while flare and wheal were recorded by the investigator. There was no qualitative or quantitative difference in 5-HT-induced itch between patients and control subjects, or between males and females. However, reduced flare and wheal were found in the patient group for 5-HT. There were no correlations between clinical findings (i.e. eczema severity, clinical pruritus) and recorded experimental itch, or flare or wheal responses for 5-HT, in the patients with AD. In both groups a shorter itch latency was found for 5-HT compared with histamine. Through the use of intradermal injections, making it possible to calculate the dose of substance delivered, a lower vascular response to 5-HT was shown in patients with AD compared with healthy controls. In addition to confirming a pruritogenic role of 5-HT in both patients with AD and healthy controls, we found a shorter itch latency for 5-HT compared with histamine in both groups. The short itch latency time may indicate a direct effect of 5-HT on itch receptors.

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