RESUMEN
CONTEXT: Cancer Pain is considered a common and significant clinical problem in malignant neoplasms, comprising 20% to 50% of all patients with tumor progression. Laser photobiomodulation (L-PBM) has been used in a multitude of pain events, ranging from acute trauma to chronic articular. However, L-PBM has never been tested in cancer pain. OBJECTIVES: Evaluate hyperalgesia, edema, COX-1, COX-2, IL-10, and Bdkrb1 mRNA in low-level laser irradiated Walker-256 tumor-bearing rats. METHODS: Rat hind paw injected with Walker Tumor-256 (W-256) and divided into six groups of 6 rats: G1 (control) - W-256 injected, G2- W-256â¯+â¯Nimesulide, G3- W-256â¯+â¯1â¯J, G4- W-256â¯+â¯3â¯Jand G5- W256â¯+â¯6â¯J. Laser parameters: λâ¯=â¯660â¯nm, 3.57â¯W/cm2, Øâ¯=â¯0.028â¯cm2. Mechanical hyperalgesia was evaluated by Randall-Selitto test. Plethysmography measured edema; mRNA levels of COX-1, COX-2, IL-10, and Bdkrb1were analyzed. RESULTS: It was found that the W-256â¯+â¯1â¯J group showed a decrease in paw edema, a significant reduction in pain threshold. Higher levels of IL-10 and lower levels of COX-2 and Bdkrb1 were observed. CONCLUSION: Results suggest that 1â¯Jâ¯L-PBM reduced the expression of COX-2 and Bdkrb1 and increasing IL-10 gene expression, promoting analgesia to close levels to nimesulide.