Assessment of the effects of laser or LED photobiomodulation on hypothyroid rats of cutaneous wound healing: A morphometric study.

Hypothyroid has been associated to a disruption of the body's metabolism, including the healing process. Laser and LED have been shown to be effective on improving healing in many situations, but their benefit in the improvement of healing on hypothyroidism remains unknown. The aim of this study was to assess, morphometrically, the influence of Laser (λ660nm, 24 J/cm², 40mW, CW, spot output= 4mm²;) and LED (λ630nm ± 20, 24 J/cm², 150mW, CW, spot output= 0.5 cm²) on the wound healing of rats with Hypothyroid. Under general anesthesia, a standard surgical wound (1cm²) was created on the dorsum of 72 male Wistar rats divided into 6 groups of 12 animals each: G1: Euthyroid; G2: Euthyroid + Laser; G3: Euthyroid + LED; G4: Hypothyroid; G5: Hypothyroid + Laser and G6: Hypothyroid + LED. Hypothyroidism was induced in rats with propylthiouracil (0.05g/100mL) administered orally for 4 weeks and maintained until the end of the experiment. Rats were irradiated after surgery each 48h then killed after 7 and 14 days. Statistical analysis was performed using ANOVA and Tukey's test. Hypothyroid rats with phototherapy laser or LED showed significant less wound contraction than euthyroid's rats at the 7^th day (p<0.05). At the 14^th day, the longitudinal measurement was significantly higher in euthyroids (control and irradiated with laser) when compared to the hypothyroid group (p <0.05). This study has shown that hypothyroidism delays wound healing and Laser and LED photobiomodulation using 24 J/cm² per session improved cutaneous wound healing in hypothyroid rats.