Melatonin Pre-treatment Alleviates UVA Radiation Induced Oxidative Stress and Apoptosis in the Skin of a Diurnal Tropical Rodent Funambulus pennanti

Abstract

UV radiation has been established as a pro-oxidant that mediates tissue injury by triggering the generation of free radicals. However UVA induced oxidative injury has never been investigated before in the skin of a tropical diurnal rodent which spends longer time directly under the sun for foraging. The present study aimed to note the level of oxidative stress induced by 6.36 Jcm-2 UVA radiations on the skin and its possible prevention by melatonin. The oxidative load was assessed by the activities of key antioxidant enzymes (superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT)) and generation of thiobarbituric acid reactive substances (TBARS). Cutaneous apoptosis if any was checked by the expression of Bcl-2, p53 and Heme oxygenase-I (HO-I). Melatonin membrane receptor expression (MT1) and AANAT activity was also investigated to elucidate the protective effect of melatonin. UVA radiation increased the lipid peroxidation, suppressed the enzymatic antioxidant defense system and increased the HO-I expression. Melatonin restored redox balance and up regulated Bcl-2 and down regulated p53 levels. The restoration of AANAT activity also proved beneficial. In summary melatonin can be a part of topical applications or oral supplements that might help to reduce the UVA radiation mediated cutaneous oxidative damages.