Hairless mouse epidermal antioxidants and lipid peroxidation assessed by He-Ne laser.

Abstract

To evaluate the possibility of oxygen radical damage in the skin after He-Ne laser irradiation according to dose intensity and time. The He-Ne laser (lambda = 632.8, 10 mW) was used on the skin of mice with 1, 3, and 5 joule (J/cm2) dose rates for 1, 5, and 7 days in each case, and the results were compared with normal and anesthetic nonirradiated skins. The efficacy was determined by the formation of thiobarbituric acid-reactive substances (TBARS) in a 10-minute period and expressed as a concentration of malondialdehyde (MDA) from the lipid peroxidation of epidermal tissue, and total superoxide dismutases (SODs) and catalase activities, correlated with histologic biopsies. Data from epidermal SODs, catalase activity and the degree of lipid peroxidation at low-power radiation showed that repeated exposure had led to the induction of free radical damage and of epidermal changes as confirmed by microscopic study. The application of the He-Ne laser at 1, 3, and 5 J intensity for 5 days caused a gradual increase in the SODs and catalase activities, while the levels of TBARS were slightly decreased in the mouse epidermis. However, these patterns were reversed after 3 and 5 J irradiations for 5 and 7 days laser treatment. Furthermore, microscopic examinations revealed that the laser-irradiated skin changed the release of stratum granule from epidermis to hair follicle, and produced blood vessel thrombosis of the dermal capillary plexus. The presence of lipid peroxidation in the hairless mouse skin after exposure to He-Ne laser energy intensity of over 3 J for over 5 days was demonstrated. This lipid peroxidation could have been generated from oxygen free radicals. The histologic and oxidative enzymatic correlations on lipid peroxidation in the skin have provided a better understanding of He-Ne laser therapy-tissue interactions. It is possible to take advantage of these findings to evaluate pathologic skin conditions and effective laser dosage more efficiently.