Laboratories of Comparative
Animal Medicine and Veterinary Molecular Pathology and Therapeutics,
Division of Animal Life Science, Institute of Agriculture, Tokyo University
of Agriculture and Technology, Tokyo, Japan.
Abnormality in skin sensitivity may be responsible for unbearable itch in patients with atopic
We evaluated reactivity of NC/Tnd mice, a model for human AD, against various experimental stimulations.
Several behavioral tests were performed after external stimuli were applied to NC/Tnd mice. Transient receptor
potential vanilloid subtype 1 (TRPV1) reactivity of neuronal cells collected from the dorsal root ganglions (DRG) was
analyzed with a Ca++ influx test. Finally, we evaluated suppressive effect of capsaicin on atopic itch of NC/Tnd mice.
Pain responses to heat, acidic stimulation, and capsaicin injection, which are transduced through TRPV1, were
decreased in NC/Tnd mice, when compared to two standard strains BALB/c and C57BL/6 mice. The reactivity of the
primary neurons isolated from DRG to capsaicin was markedly reduced in NC/Tnd mice. Topical application of histamine
evoked scratching in NC/Tnd mice as well as other two strains; however, the scratching intensities induced by nonhistamine
pruritogens were significantly lower in NC/Tnd mice comparing to the two strains. In conventional NC/Tnd
mice with AD, topical application of capsaicin reduced the scratching behavior.
TRPV1 is associated with both pain and itch sensation; however, abnormalities in TRPV1 reactivity may involve
in severe itch in NC/Tnd mice.