Degree of ultraviolet-induced tortuosity of elastic fibers in rat skin is age dependent.
To elucidate differential effects of ultraviolet (UV) exposure on three-dimensional networks of elastic fibers during maturation of rat skin, Sprague-Dawley rat hind limbs were irradiated with suberythemal doses of UV light (UVB, 130 mJ/cm2, or UVA, 27 J/cm2) in three different time courses of exposure: 3-9 weeks old, 9-15 weeks old, and 3-15 weeks old. Three-dimensional arrangement with special reference to linearity of elastic fibers was quantified by image analysis using a scanning electron microscope after a combination of intravascular resin injection and selective digestion technique using formic acid. Among the three irradiation groups, the group irradiated with UVB or UVA between 3 and 15 weeks old (UVB, three times per week; UVA, five times per week) elicited the most marked decrease in the linearity of elastic fibers. Despite the same irradiation period, there was a significant difference in the decreased linearity between the two irradiation groups of 3-9 and 9-15 weeks old, with the former irradiation group exhibiting greater loss of linearity than the latter irradiation group. The magnitude of the decreased linearity was greater in the UVB-exposed groups than in the UVA-exposed group. These findings indicate that the three-dimensional linearity of elastic fibers is more susceptible to disruption by UV exposures during the growth period than that after the growth period.
Imokawa
G
G
Institute for Fundamental Research, Kao Corporation, Tochigi, Japan.
Takema
Y
Y
Yorimoto
Y
Y
Tsukahara
K
K
Kawai
M
M
Imayama
S
S
D000375:Aging / Q000502:physiology*; D000818:Animals; D004547:Elastic Tissue / Q000528:radiation effects* / Q000648:ultrastructure*; D008297:Male; D008855:Microscopy, Electron, Scanning; D051381:Rats; D012867:Skin / Q000528:radiation effects* / Q000648:ultrastructure*; D014466:Ultraviolet Rays