The Preventive and Protective Mechanisms of Melatonin in Experimental Periodontal Disease in Rats

Chronic periodontitis is one of the most common oral diseases characterized by inflammation and destruction of the periodontal supporting tissues. It is initiated by periodontal bacteria within the plaque biofilm, and the disease progression depends on the host immune system. During periodontitis, reactive oxygen species (ROS) and inflammatory cytokines are released from immune system to defense the periodontal pathogens. Recently, oxidative stress has been considered as an important role in the periodontal tissue destruction and systemic inflammation. Melatonin, a hormone secreted by the pineal gland, works directly and indirectly as an immune and antioxidant modulator. Previous clinical studies demonstrated the negative association between melatonin levels in saliva or serum and the severity of periodontitis. However, the exact role of melatonin in the prevention and treatment of periodontal disease remains unclear. Furthermore, the exact mechanism involved in such response is needed to be explored. Therefore, the aims of this study are to investigate the protective effect, preventive effect, immune modulatory and antioxidant capacity of melatonin in experimental periodontitis in rats, and to evaluate the molecular mechanisms of melatonin’s anti-inflammatory and antioxidant actions. Based on this viewpoint, the present study was designed to assess (1) the protective effects, preventive effects, anti-inflammatory and antioxidant abilities of melatonin on the treatment of periodontitis by using three-dimensional scanning, histological, immunohistochemical and biochemical methods and to evaluate (2) the molecular mechanism of melatonin in the anti-inflammatory and antioxidant actions by using biochemical methods, real-time PCR and Western blotting. With the completion of this two-year research project, we not only provide the histological, immunohistochemical, biochemical and molecular evidences of the melatonin’s therapeutic abilities, but also provide valuable information and references of melatonin’s anti-inflammatory and antioxidant functions for further clinical studies and clinical applications.