Assessment of relief from pruritus due to Kampo medicines by using murine models of atopic dermatitis

Abstract

Aim: Atopic dermatitis is a representative intractable chronic eczematous skin disease. Because the symptoms vary between individuals, several therapies are required for atopic dermatitis. Since kampo medicines should be used according to the particular physical and mental conditions, the use of distinctive animal models is necessary for the experimental assessment of the effi cacy of kampo medicines. In this study, 7 kampo medicines were assessed for their anti-itching eff ect in 2 types of atopic dermatitis-like pruritus models for characterizing. Methods: Long-lasting scratching behavior was induced by multiple treatments with 2,4,6-trinitrochlorobenzene (TNCB) for 4 weeks in NC mice. Kampo medicines were administered orally for 11 d from the following day of the last TNCB-treatment to assess curing pruritus. In the other model, TNCB was applied to ears of BALB/c mice for 10 d every other day to induce scratching behavior. Kampo medicines were administered orally everyday for the same term of the induction of scratching behavior to assess the prevention of dermatitis. Results: Shofusan (SFS) had an instant eff ect, even on using a single dose, on scratching behavior in the model of NC mice; it ameliorated chronic itching on oral administration for 11 d, by preventing mast cell diff erentiation and degranulation. In the model of BALB/c mice, another kampo medicine, hochuekkito (HET) inhibited the induction of scratching behavior. Conclusion: Kampo medicines such as SFS and HET may improve chronic itching sensation in atopic dermatitis to the same extent as or better than existing antiallergic medicines.