WAVELENGTH DEPENDENCE OF HISTOLOGICAL, PHYSICAL, AND VISIBLE CHANGES IN CHRONICALLY UV‐IRRADIATED HAIRLESS MOUSE SKIN*

Abstract

— Albino hairless mice (Skh:HR–1) exposed chronically to sub-erythemal doses of UV radiation display physical, visible and histological alterations. Using narrow bandwidth radiation covering the UV radiation spectrum from280–380 nm, the wavelength dependence of these alterations was determined. The wavelength dependence spectra indicate that for all but one parameter measured (skin sagging), UV-B radiation is considerably more efficient than UV-A radiation in producing changes in the skin. However, in natural sunlight there is considerably more UV-A than UV-B radiation, providing the potential for UV-A to have a larger contribution to skin damage than UV-B. This argues in favor of using broad spectrum photoprotective agents to shield the skin adequately from UV-induced aging. The spectra were also used to develop potential associations among events by determining which events occur at similar wavelengths. There seems to be a correspondence between mouse visible skin wrinkling (UV-B event) and two histological events: increase in glycosami-noglycans and alteration in collagen. There was no obvious correspondence among UV-A-induced events.