BACKGROUND: Therapeutic use of low-level laser in physical therapy has increased significantly. OBJECTIVE: To assess the effects of low-level laser therapy on the oxidative parameters of wound healing in rats. METHODS: Eighteen Wistar rats were randomly divided into three groups (control, 5 days, n=6; 2 J/cm², 5 days, n=6; 4 J/cm², 5 days, n=6). A single circular wound measuring 8 x 8 mm was surgically created on the rats' backs. Thirty minutes after the last irradiation, the rats were euthanized and the irradiated tissue was surgically removed and stored at -70°C. We determined the activity of the respiratory chain enzymes DCIP oxidoreductase (complex II) and soluble succinate dehydrogenase (SDH); the activity of cytochrome c oxidase (complex IV); the production of superoxide anion; and the activity of superoxide dismutase (SOD) and catalase (CAT). Lipid peroxidation was assessed by means of the TBARS assay. RESULTS: There was a decrease in the complex II activity in the groups irradiated for 5 days with 2 and 4 J/cm², while superoxide anion production decreased significantly in the group irradiated for 5 days with 4 J/cm² when compared with the control group. There was also a significant increase in CAT activity in the group irradiated for 5 days with 2 J/cm² as well as a decrease in lipid peroxidation activity in the two irradiated groups. CONCLUSIONS: The results of the present study indicate that laser stimulates antioxidant activity and protects cells against oxidative damage during the wound healing process in rats.
wound healing; low-level laser therapy; oxidative stress; respiratory chain; free radical
