Effects of low-level laser therapy (LLLT) on the nuclear factor (NF)-κB signaling pathway in traumatized muscle

Background and Objective: To investigate the effects of low-level laser therapy (LLLT) on nuclear factor kappa B (NF-kappa B) activation and inducible nitric oxide synthase (iNOS) expression in an experimental model of muscle trauma. Study Design/Materials and Methods: Injury to the gastrocnemius muscle in the rat was produced by a single impact blunt trauma. A low-level galium arsenide (Ga-As) laser (904 nm, 45 mW, and 5 J/cm(2)) was applied for 35 seconds duration, continuously. Results: Histological abnormalities with increase in collagen concentration, and oxidative stress were observed after trauma. This was accompanied by activation of NF-kappa B and upregulation of iNOS expression, whereas protein concentration Of I kappa B alpha decreased. These effects were blocked by LLLT. Conclusion: LLLT reduced the inflammatory response induced by trauma and was able to block the effects of reactive oxygen species (ROS) release and the activation of NF-kappa B. The associated reduction of iNOS overexpression and collagen production suggest that the NF-kappa B pathway may be a signaling route involved in the pathogenesis of muscle trauma.