Induction of scratching behaviour and dermatitis in various strains of mice cohabiting with NC/Nga mice with chronic dermatitis

Summary Background  NC/Nga (NC) mice with similar pathological and behavioural features as seen in human atopic dermatitis are used as a model of the disease. Under normal circumstances, spontaneous and persistent scratching occurs in NC mice and this can lead to the onset of skin inflammation. Objectives  We examined the induction of scratching behaviour in NC, BALB/c, ICR and C3H/HeN mice, and of dermatitis in NC and BALB/c mice, by cohabitation with mice with dermatitis. Methods  NC, BALB/c, ICR and C3H/HeN mice were kept together with NC mice with chronic dermatitis (CNV‐NC) for 2 weeks, and the numbers of scratching episodes were counted. NC and BALB/c mice were also kept together with CNV‐NC mice for 24 weeks and the skin severity score was assessed. The score was assessed for a further 8 weeks after separation of these mice. Results  The number of scratching episodes in NC, BALB/c, ICR and C3H/HeN mice was increased by cohabitation with CNV‐NC mice. Cohabitation with CNV‐NC mice led to dermatitis in both NC and BALB/c mice. The number of scratching episodes and the skin severity score in BALB/c mice were about half of those in NC mice. When cohabitation with CNV‐NC mice stopped, the number of scratching episodes and the skin severity score decreased in BALB/c mice, but not in NC mice. Changes in the histopathological data of BALB/c mice supported the severity of skin inflammation. Conclusions  Our study demonstrates that scratching behaviour and dermatitis can be induced in various strains of mice by cohabitation with CNV‐NC mice, and that cessation of cohabitation leads to a recovery in BALB/c mice but not in NC mice.