Histopathological Evaluation of the Effects of Melatonin as a Protectant Against Oropharyngeal Mucositis Induced by Radiation Therapy in a Pinealectomy Model in Rats

This study presents the histopathological evaluation of the effects of melatonin as a protectant against oropharyngeal mucositis induced by radiation therapy in a pinealectomy model in rats. Thirty-two Wistar rats were divided into four groups. The rats in Group 1 underwent pinealectomy, received melatonin and underwent radiation therapy. The rats in Group 2 underwent pinealectomy, received no melatonin and underwent radiation therapy. The rats in Group 3 underwent sham pinealectomy, received melatonin and underwent radiation therapy. The rats in Group 4 underwent sham pinealectomy, received no melatonin and underwent radiation therapy. The rats underwent euthanasia at six days following radiation therapy. The oropharyngeal tissues were dissected and histopathological evaluation was performed regarding the effects of melatonin as a protectant against oropharyngeal mucositis induced by radiation therapy. Mean item scores for vascular calibration were 2.3 points for Group 1, 2.3 points for Group 2, 1.8 points for Group 3 and 2.1 points for Group 4 (p= 0.44). Mean item scores for vascular permeability were 2.4 points for Group 1, 2.4 points for Group 2, 2.0 points for Group 3 and 2.1 points for Group 4 (p= 0.61). Mean item scores for leukocyte emigration were 2.0 points for Group 1, 2.0 points for Group 2, 1.3 points for Group 3 and 1.6 points for Group 4 (p= 0.02). Mean overall scores for oropharyngeal mucositis were 6.6 points for Group 1, 6.6 points for Group 2, 5.1 points for Group 3 and 5.8 points for Group 4 (p= 0.15). This study elicits the potential effects of melatonin as a protectant against oropharyngeal mucositis induced by radiation therapy.