Skin morpholoDy at the time of UV irradiation is important for wrinkle formation

Hairless mice (HR/ICR) were irradiated chronically with suberythemal doses of UV-B radiation (ultraviolet radiation in wavelength 290-320 nm) immediately before and after production, with cyanoacrylate r sin, of an artificial temporary groove parallel to the midline, which is an unusual direction for wrinkle formation. Data for UV radiation-exposed skin beibre or after production of an artificial groove and in chronological age-matched control mice or mice treated only by production of an artificial temporary groove were compared. Visible signs of artificial wrinkling were present after approximately six weeks of UV-B irradiation and were very apparent after ten weeks of irradiation. From image analysis of skin impressions after ten weeks, artificial wrinkling in skin treated by UV-B irradiation after production of an artificial groove was significantly increased compared with skin in which an artificial groove was produced after UV-B irradiation. These results indicated that both an artificial temporary groove in the skin and UV-B irradiation immediately after production of the temporary groove are necessary for wrinkle formation in this mouse model, and suggested that the skin morphology at the time of UV-B irradiation is important for wrinkle formation.