Quantitative and quanlitative changes of collagen in ultraviolet irradiated skin of hairless mice / 中华医学美学美容杂志

ABSTRACT

Objective To study collagen changes in dermis of hairless mice that were exposed to ultraviolet. Methods The hairless mice was irradiated under UVA, UVB and the combination of the two for 20 weeks, total dose of UVA was 222J/cm~2, and that of UVB was 5.9J/cm~2. After irradiation, the dorsal skin's collagens of animals were analysed by computer imaging analysis system, histopathologic examination, specific stains and electorn microscopy. Results The hairless mice exposed to ultraviolet A were unchanged in dermis collagen. The hairless mice was irradiated under UVB and the both UVA and UVB, and the content of collagen was decreased with less affinity for collagen staining. These findings were supported by electron microscopy, which showed fraying, thickened, and proliferating collagen, coalesced into extensive denaturalization. The ratio of types Ⅲ/Ⅰ+Ⅲ collagen was significantly increased. Conclusion The qualitative and quantitative changes of the collagen in the ultraviolet irradiated skin of hairless mice are related to ultraviolet B but not to UVA. UVB is a key factor of skin collagen damage in UV-irradiation.