TITLE:
Topical Application of Tenshino-SoftgelTM Reduces Epidermal Nerve Fiber Density in a Chronic Dry Skin Model Mouse
AUTHORS:
Atsushi Noguchi, Mitsutoshi Tominaga, Kyi Chan Ko, Hironori Matsuda, Yasushi Suga, Hideoki Ogawa, Kenji Takamori
KEYWORDS:
Dry Skin, Emollient, Epidermal Nerve Fiber, Itch, Skin Barrier
JOURNAL NAME:
Journal of Cosmetics, Dermatological Sciences and Applications,
Vol.5 No.4,
November
25,
2015
ABSTRACT: Background: Dry skin induces antihistamine-resistant itch, as well as epidermal
hyperinnervation, which is partly responsible for peripheral itch
sensitization. In acute dry skin, topical application of emollients prevents
the penetration of nerve fibers into the epidermis. However, the effects of
emollients on itch and epidermal hyperinnervation in individuals with chronic
dry skin are poorly understood. Objective: This study examined the effects of Tenshino-softgelTM (TSG) on itch-related behavior, epidermal hyperinnervation and skin barrier
function in a chronic dry skin model mouse. Methods: Chronic dry skin was
induced by application of acetone/ether (1:1) mixture and water (AEW) to the
rostral parts of the back of hairless mice twice daily for six consecutive
days. As treatment, TSG or, as control, Vaseline (V) was applied to the same
areas twice daily. Skin barrier function was evaluated by measuring
transepidermal water loss (TEWL) before each treatment. Scratching behavior was
recorded and analyzed using a SCLABA®-real system, and skin samples
were collected for immunohistochemical assays. Results: TEWL tended to be lower
and scratching bouts fewer in AEW + TSG- than in AEW-treated mice. The numbers
of protein gene product 9.5-immunoreactive fibers and substance
P-immunoreactive fibers were each significantly lower in the epidermis of AEW +
TSG- than of AEW-treated mice, but the expression of nerve growth factor in
epidermis was similar in the three groups. Semaphorin 3A expression was significantly
higher in the epidermis of AEW + TSG- than of AEW- and AEW + V-treated mice.
Conclusion: Topical application of TSG may attenuate itch induced by chronic
dry skin through a mechanism involving the inhibition of epidermal
hyperinnervation.