Evaluation of LED Photobiomodulation on Wound Healing in Hypothyroid and Euthyroid Rats

Thyroid hormone deficiency has been associated to disruption of the body's metabolism, including healing process. LED phototherapy has been shown to be effective in improving healing in many situations, but their usefulness in the improvement of hypothyroidism wound healing remains unknown. The aim of this study was to assess histologically the effect of LED (lambda 630 +/- 20nm, 150mW, CW, phi=0.5 cm(2), 24J/cm(2) per session) on wounds healing in hypothyroid and euthyroid Wistar rats. Standard cutaneous wound (1cm(2)) was created on the dorsum of 24 animals divided into four groups of 6 animals each: G1: Euthyroid; G2: Euthyroid + LED; G3: Hypothyroid; G4: 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. The irradiation started immediately after surgery and was repeated every other day for 7 days. Animals were killed 8 days after surgery. The specimens were removed, routinely processed and stained with H&E and Sirius red. Statistical analysis was performed using the Fisher's Test and significance level was 5%. The results of the present investigation showed delayed wounds healing process in hypothyroid rats characterized by incomplete reepithelialization and formation of disorganized collagen fibers (p<0.05) when compared to the euthyroid group, and that in the irradiated groups the reepithelialization was statistically higher when compared with non-irradiated ones (p<0.05). There was improved collagen fibers deposition on irradiated animals (euthyroid and hypothyroid) when compared to non-irradiated ones, but no statistically significant difference (p>0.05). It is concluded that LED light has a positive biomodulative effect on the wound healing process, even when hipothyroidism was present.