OXIDATIVE STRESS AND IN-VIVO CHEMILUMINESCENCE IN MOUSE SKIN EXPOSED TO UVA RADIATION

Mouse skin was exposed to UVA radiation (320-400 nm). The in vivo chem iluminescence of the skin was measured after irradiation. Chemilumines cence showed a maximum 13-fold increase (control emission, 10+/-1 cps cm(-2)) after 45-60 min of exposure to UVA, with no further increase w ith 60 min additional exposure. Spectral analysis of the emitted chemi luminescence showed that the principal species emitted in the 400-500 nm range. Topical application with alpha-tocopherol (10% v/w) and beta -carotene (1 mM) greatly reduced the UVA-induced skin chemiluminescenc e. Thiobarbituric acid reactive substance (TEARS) levels were increase d by 130% in skin homogenates after 2 h of exposure to UVA (control va lue, 77 +/- 14 nmol malonaldehyde equivalents (g tissue) (-1)). The ac tivities of antioxidant enzymes in skin homogenates were decreased aft er 2 h of irradiation: the superoxide dismutase (SOD) activity (contro l value, 181+/-10 U SOD (g tissue)(-1)) was decreased by 40% and the c atalase activity (control value, 1.34+/-0.14 pmol (g tissue)(-1)) was decreased by 45%. In vivo chemiluminescence appears to be a suitable m ethod for following the kinetics of the skin oxidative stress processe s and for testing the effect of topical application with antioxidants and photoprotective agents. (C) 1997 Elsevier Science S.A.