Attenuation of DNA damage in the dermis and epidermis of the albino hairless mouse by chronic exposure to ultraviolet-A and -B radiation

Mammalian skin is vulnerable to the photocarcinogenic and photoaging effect s of solar UV radiation and defends itself using a variety of photoprotecti ve responses including epidermal thickening, tanning and the induction of r epair and antiradical systems. We treated Skh-1 albino hairless mice for 60 days with ultraviolet-A (UVA) or ultraviolet-B (UVB) radiation and measure d the frequency of cyclobutane pyrimidine dimers and pyrimidine(6-4)pyrimid one photoproducts induced by a single acute sunburn dose of UVB at differen t stages of the chronic treatment. Wt found that both UVA and UVB exposure produced a photoprotective response in the dermis and epidermis and that th e degree of photoproduct attenuation was dependent on dose, wavelength and the type of damage Induced. Although epidermal thickening was important, ou r data suggest that UV protective compounds other than melanin may be invol ved in mitigating the damaging effects of sunlight in the skin.