Background and aims: Diabetic neuropathy develops as a complication of diabetes. No used treatment focused on curbing the development of mechanical hyperalgesia. Efficacy of photobiomodulation therapy (PBMT) in painful clinical conditions has been established by several recent studies. The aim of this study was to verify the preventive effect of PBMT against the development of mechanical hyperalgesia on streptozotocin (STZ)-induced diabetic neuropathic rats. Methods: Experiments were approved by the UNICAMP Ethic's Commitee (#3902-1). Male Lewis rats (200-250 g; 6-8-weeks-old) received a STZ-low-dose (Sigma-Aldrich®, 25 mg/kg) once a day, during five consecutive days. Diabetic animals (250 mg/dL of glucose) were submitted to Randall-Selitto test at 7, 10, 14, 17, 21, 24 and 28 days after STZ injections. After the 7th day, rats were submitted to daily PBMT (GaAs 904 nm, 70 mW) under three different laser total energies: 2.03 J (29 seconds); 4.06 J (58 seconds); 8.12 J (116 seconds). PBMT was performed transcutaneously at the dorsal region between L4/L5 dorsal root ganglia (DRG) (bilateral). Results: PBMT was able to partially prevent the development of hyperalgesia (Δ withdrawal threshold, g), especially for the 2.03 J total energy, when compared to diabetic neuropathic non-irradiated rats [at the 14th (p< 0.001), 17th (p< 0.05), 21st (p< 0.05), 24th (p< 0.001), and 28th (p< 0.01) days; Two-Way ANOVA followed by Bonferroni post hoc test]. Conclusions: Data of this study suggest that PBMT could be a promising tool to helping prevent the development of hyperalgesia linked to diabetic neuropathy.

PREVENTIVE EFFECTS OF PHOTOBIOMODULATION THERAPY (904 NM) DURING THE DEVELOPMENT OF DIABETIC NEUROPATHIC HYPERALGESIA