Investigation of the Comparative Effects of Red and Infrared Laser Therapy on Skeletal Muscle Repair in Diabetic Rats

Objective: The aim of this study was to evaluate the in vivo response of 2 different laser wavelengths (red and infrared) on skeletal muscle repair process in diabetic rats. Design: Forty Wistar rats were randomly divided into 4 experimental groups: basal control-nondiabetic and muscle-injured animals without treatment (BC); diabetic muscle-injured without treatment (DC); diabetic muscle-injured, treated with red laser (DCR) and infrared laser (DCIR). The injured region was irradiated daily for 7 consecutive days, starting immediately after the injury using a red (660 nm) and an infrared (808 nm) laser. Results: The histological results demonstrated in both treated groups (red and infrared wavelengths) a modulation of the inflammatory process and a better tissue organization located in the site of the injury. However, only infrared light significantly reduced the injured area and increased MyoD and myogenin protein expression. Moreover, both red and infrared light increased the expression of the pro-angiogenic vascular endothelial growth factor and reduced the cyclooxygenase 2 protein expression. Conclusion: These results suggest that low-level laser therapy was efficient in promoting skeletal muscle repair in diabetic rats. However, the effect of infrared wavelength was more pronounced by reducing the area of the injury and modulating the expression proteins related to the repair.