Epidermal proliferative response induced by sodium dodecyl sulphate varies with environmental humidity.
BACKGROUND
Previous studies have suggested that susceptibility of skin to external agents increases in the dry winter season.


OBJECTIVE
To test the hypothesis that environmental humidity affects skin sensitivity to irritants.


METHODS
The epidermal hyperplasia induced by sodium dodecyl sulphate (SDS) under various humidity conditions was evaluated on the skin of hairless mice.


RESULTS
Mice kept under low humidity for 2 days showed more obvious epidermal proliferation 24 h after topical application of SDS than those kept under high or normal humidity for 2 days. In contrast, mice kept under high humidity for 2 weeks showed more obvious epidermal proliferation 24 h after topical application of SDS than those kept under low or normal humidity. The transepidermal water loss was altered significantly in the animals kept under high humidity for 2 weeks, although it was not altered during the first 7 days under either low or high humidity.


CONCLUSIONS
These results suggest that environmental humidity influences the sensitivity of skin to topical application of SDS and that increased sensitivity is not always associated with alteration of the water impermeability of the stratum corneum.
Denda
M
M
Shiseido Research Center, 2-12-1 Fukuura, Kanazawa-ku, Yokohama 236-8643, Japan. mitsuhiro.denda@to.shiseido.co.jp
D000704:Analysis of Variance; D000818:Animals; D004817:Epidermis / Q000187:drug effects* / Q000473:pathology / Q000502:physiology; D006813:Humidity; D006965:Hyperplasia / Q000139:chemically induced; D051379:Mice; D008812:Mice, Hairless; D012967:Sodium Dodecyl Sulfate / Q000494:pharmacology*; D013501:Surface-Active Agents / Q000494:pharmacology*; D014870:Water Loss, Insensible / Q000502:physiology
D013501:Surface-Active Agents; D012967:Sodium Dodecyl Sulfate