We aimed to develop an animal model for atopic dermatitis. HR-1 hairless mice fed a diet with reduced magnesium and zinc levels were compared with mice fed a standard diet. Skin dryness and wrinkle-like changes, scratching behaviour, decreased skin water content, increased transepidermal water loss and raised blood immunoglobulin E levels were seen in the group receiving the reduced magnesium and zinc diet compared with control mice. There were no significant differences in body weight or the weight of the major organs between the two groups. Haematological examination in both groups was normal apart from increased immunoglobulin E levels in mice fed a reduced magnesium and zinc diet. These mice may be useful models of atopic dermatitis; preparation of the animals is not particularly time consuming, the reproducibility is 100%, and atopic dermatitis symptoms occur even in a specific pathogen-free environment.

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Fexofenadine, a histamine H1-receptor antagonist, is approved for the treatment of pruritus associated with atopic dermatitis. The effects of fexofenadine on scratching behaviour, and plasma levels of histamine and eotaxin were assessed in a new model of atopic dermatitis. Mice fed a diet low in Mg2+ and Zn2+ (special diet S) were compared with mice on a normal diet (N) or diet S plus fexofenadine HCl for weeks 0-10 (S + F(0-10)), 0-5 (S + F(0-5)) or 6 - 10 (S + F(6-10)) (seven mice per group). Compared with group N, group S mice showed significantly greater scratching frequency, and plasma histamine and eotaxin concentrations; these three variables were significantly lower in group S + F(0-10) than in group S. Scratching frequency increased when fexofenadine was discontinued. Fexofenadine significantly reduced mast cell and eosinophil numbers. Histamine may be important in the pathological changes seen in this model of atopic dermatitis, suggesting that it might aid future development of antihistamines for the treatment of atopic dermatitis.

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