Experimental Study For Effects Of Oral Lycopene On UVA-Induced Skin Photoaging In Rats

Background and Aims: Chronic solar ultraviolet exposure causes photoaging of skin, a process that is characterized by wrinkles, loss of skin tone and resilience. Ultraviolet A (UVA,320~400nm) is the main part of solar ultraviolet which account for 95% or more of total ultraviolet radiation on the surface of the globe. UVA can penetrate into the deep layers of skin and plays a key role in the pathogenesis of skin photoaging. With the increasing understanding of the molecular mechanism of photoaging, UV-generated reac -tive oxygen species (ROS) have been determined as key factors in the induction of photoaging. Therefore,it is possible for antioxidant to act as a new protective strategy to prevent skin photoaging,but cogent evidences are absent. The aim of present study is to explore effects of oral antioxidant lycopene on UVA-induced skin photoaging in rats. Methods: Rats were divided into three parts comprising control group(C), ultraviolet exposed group(UV), and ultraviolet exposed and lycopene-treated group(UV+L). Rats of UV group and UV+L group were irradiated with UVA radiation. In rats of UV+L group lyc -opene was gavaged before irradiation. Appearance and histological configuration of skin were studied by hematoxylin-eosin stain and Verhoeff van Gieson stain. Malonaldehyde (MDA),an end product of lipid-peroxidation, was measured by thiobarbituric acid reactive substances(TBARS) assay in the skin. Semi-quantitative reverse transcript PCR (sqRT-PCR) and immuhistochemistry(ICC) were used to detect the expression of metal matrixproteinas -es(MMPs) in skin. Results:1. UVA radiation used in our studies had no obvious influence on the appearance and histological configuration of skin in rats.2. The levels of MDA in UV group and UV+L group significantly increased following UVA when compared with those in controls(p<0.01). MDA levels in UV+L group were significantly lower than those in UV group(p<0.01).3. The levels of MMP-1,MMP-2 and MMP-9 expression in the UV group and UV+L group significantly increased following UVA irradiation when compared with those incontrols(p<0.01). In UV+L group the levels of MMP-1,MMP-2 and MMP-9 expression were all lower than those in UV group.Conclusion: Oral lycopene has evident antagonistic effects on formation of MDA and over-expression of MMPs induced by UVA radiation in rats,which indicated that systemic use of lycopene may prevent UVA-induced photoaging in rats.