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[A-4.6 Studies on the effects of oxidative stress due to UV-B irradiation]

[Contact Person]

Margarita Dimitrova Apostolova, Ph.D
Noriko Nishimura, Ph.D
Chiharu Tohyama, Ph.D
National Institute for Environmental Studies
Environmental Agency
Onogawa 16-2, Tsukuba, Ibaraki, 305 Japan
Tel:+81-298-50-2336, Fax:+81-298-56-4678
e-mail: ctohvama@nies.go.jp

[Total Budget for FY1995]

4,501,000Yen

[Abstract]

　Ultraviolet B radiation results in the generation of oxidative stress in the tissue. Understanding the mechanisms of antioxidant self-defense system and their role in skin maintenance and function as well as the role of metal-dependent systems in responding to ultraviolet radiation may offer a new approach for preventing and/or treating radiation injury. In order to elucidate how antioxidant system is involved in this process, we have studied possible protective roles of metallothionein in the skin against daily UV-B radiation and the eventual compensatory mechanisms by utilizing transgenic mice whose MT gene were knocked out by homologous recombination. It was found that MT-null mice were less sensitive to UV-B radiation in comparison with their ancestors C57BL/6J and 129-SV mice. The MT-null mice contained the lowest skin NPSH levels compared to the other two mice strains, but had the greatest GSH-Px activity after ultraviolet radiation. A dose-dependent increase of TBA-RS were found in MT- null mice in comparison with C57BL/6J and 129-SV mice. Taken together, the present results indicated that the sensitivity of the skin to UV-B irradiation was not necessarily associated with the endogenous MT synthesis, but that the protective role of MT against free radical could not be excluded.

[Key Words]

Metallothionein, UV-B, MT-null mice, interleukins