Background: The aim of this study was to evaluate the effects of systemic melatonin treatment on serum oxidative stress index and alveolar bone loss in diabetic rats with periodontitis.

Methods: Seventy Sprague Dawley rats were divided into control (C), experimental periodontitis (EP), diabetes (DM), EP-DM, EP–melatonin (EP-MEL), DM-MEL and EP-DM-MEL groups. Diabetes was induced by alloxan, after which periodontitis was induced by ligature for four weeks. After removal of the ligature, the rats in the melatonin groups (EP-MEL, DM-MEL, and EP-DM-MEL) were treated with a single dose of melatonin (10 mg/bw) every day for 14 consecutive days. At the end of the study, all of the rats were euthanized and intracardiac blood samples and mandible tissues were obtained for biochemical and histological analyses. Serum levels of total oxidant status / total antioxidant status and oxidative stress index (OSI) were measured. In addition, neutrophil and osteoclast densities and myeloperoxidase activities were determined in gingival tissue homogenates, and alveolar bone loss was evaluated with histometric measurements.

Results: Melatonin treatment significantly reduced fasting plasma glucose levels in the diabetic rats. In addition, reduced OSI and alveolar bone loss levels were detected in the EP-MEL and DM-MEL groups; the reductions in the EP-DM-MEL group were found to be more prominent. Melatonin also significantly decreased the increased myeloperoxidase activities and osteoclast and neutrophil densities in the EP, DM, and EP-DM groups.

Conclusion: It was revealed in this experimental study that melatonin significantly inhibited hyperglycemia-induced oxidative stress and alveolar bone loss through antidiabetic and antioxidant effects in diabetic rats with periodontitis.

KEYWORDS: Anti-inflammatory agents, antioxidant(s), diabetes, experimental periodontitis, oxidative stress, melatonin