Oxidative stress and in vivo chemiluminescence in mouse skin exposed to UVA radiation

Abstract

Mouse skin was exposed to UVA radiation (320–400 nm). The in vivo chemiluminescence of the skin was measured after irradiation. Chemiluminescence 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 with 60 min additional exposure. Spectral analysis of the emitted chemiluminescence showed that the principal species emitted in the 400–500 nm range. Topical application with α-tocopherol (10% v/w) and ß-carotene (1 mM) greatly reduced the UVA-induced skin chemiluminescence. Thiobarbituric acid reactive substance (TBARS) levels were increased by 130% in skin homogenates after 2 h of exposure to UVA (control value, 77 ± 14 nmol malonaldehyde equivalents (g tissue) −1). The activities of antioxidant enzymes in skin homogenates were decreased after 2 h of irradiation: the superoxide dismutase (SOD) activity (control value, 181 ± 10 U SOD (g tissue) −1) was decreased by 40% and the catalase activity (control value, 1.34 ± 0.14 pmol (g tissue) 1) was decreased by 45%. In vivo chemiluminescence appears to be a suitable method for following the kinetics of the skin oxidative stress processes and for testing the effect of topical application with antioxidants and photoprotective agents.