Journal of dermatological science
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To clarify the behavioral and pathological features of spontaneous scratching of NC mice with mite-induced chronic dermatitis, we investigated the spontaneous and pruritogen-evoked scratching of NC mice. Although the frequency of scratching of NC mouse did not increase under specific pathogen-free environment, it gradually and markedly increased from 3 to 6 weeks after transfer to conventional environment. The onset of increase in spontaneous scratching was similar to that of dermatitis development and the elevation of plasma concentration of immunoglobulin E. ⋯ Methysergide and cyproheptadine inhibited the serotonin-induced scratching but not spontaneous scratching. The results suggest that marked elevation of plasma immunoglobulin E is not always the cause of spontaneous itch-associated response of NC mice with dermatitis. Serotonin, histamine and substance P may not play an important role in spontaneous itch-scratch response at a chronic stage.