Background :
@EN Photoaging skin is clinically characterized by wrinkled, dry, inelastic and irregularly pigmented skin, skin tumor and histologically by increased epidermal thickness , numerous fibroblasts, mast cells and inflammatory cells in the upper
dermis,
elastosis, degeneration of collagen fibers, increased proportion of type III collagen fibers in the dermis and increased numbers of keratinizing cysts in the lower dermis of hairless albino mouse skin. Chronic exposure to UVB induces photoaging
skin and
sunscreen agents are used to prevent phovodamage to skin and reduce the incudence and extent of the chronic photoaging effects.
@ES Objective :
@EN To evaluate the photoaging effects of UVB on the skin and to assess the ability of sunscreen agents to protect the skin from photoaging, we examined the clinical, histological and quantiative changes in collagen in the skin of Albino hairless
Skh.
HR-1 mice.
Materials and Methods : The experimental animals were male Albino hairless Skh: HR-1 mice, 12 weeks old. The control group was a chronologically aging group which had not been affected weekly(Monday, Wednesday, Friday), for 12 weeks. To assess
the
photoprotective effects of sunscreen agents, the control group, the non-protected group and the sunscreen agent-applicated groups were compared to each other clinically, histologically, and by quantitative collagen analysis. An early increase in
type
III collagen during UVB irradiation was determined by cyanogen bromide digestion of the whole skin, sodium dodecyl sulfate-polyacrylamide gel electuophoresis and densitometry.
@ES Results :
@EN Clinically, the skin of the mice in the non-protected group showed mild changes caused by photoaging. Histologically, the non-protected group showed increases in the size and umber of keratinizing cysts in the lower dermis and increases in
the
mast
cells in the upper derthickness, iflammatory cell infiltration, elastic fiber change or degeneration of collagen fibers were shown. By the 12th week, four of the total of nine mice in the non-protected group developed at least one tumor. The
sunscreen
agent applicated groups showed slightly photoprotected effects clinically and histologically. In the collagen analysis, the proportion of type III collagen was significantly increased in the photoaging skin of mice in the non-protected group
compared
with the control group. Mice in the sunscreen agent applicated groups showed a significantly decreased proportion of type III collagen compared with the non-protected group.
@ES Conclusion :]
@EN To summarize, UVB exposure of the skin induces photoaging. The number and size of keratinizing cysts increased in the photoaging skin of hairless albino mice. There was also a quantitative change in the collagen fibers. The use of sunscreen
agents
decreases the photoaging effects of UVB on the skin. (Kor J Dermatol 1996;324(1) : 289~299)
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