Conclusion
Green tea intake reduces expression of the pro-inflammatory cytokine TNF-α and the osteoclastogenic mediator RANKL to normal levels while increasing expression of the anti-inflammatory cytokine IL-10, the osteogenesis-related factor RUNX-2 and the anti-osteoclastogenic factor OPG. Therefore, green tea represents a potential therapeutic agent for the treatment of diabetes-related periodontal disease.
Methods
Diabetes was induced in rats via a single intraperitoneal injection of streptozotocin (STZ). Diabetic and control animals were divided into water-treated and green tea-treated subgroups and were analyzed at 15, 30, 60 and 90 days after diabetes induction. Immunohistochemistry was performed to quantitatively evaluate tumor necrosis factor-α (TNF-α), receptor activator of nuclear factor kappa-B ligand (RANKL), osteoprotegerin (OPG), interleukin-10 (IL-10) and runt-related transcription factor 2 (RUNX-2) expression in serial sections of each hemimaxilla. Morphometric measurements of the distance from the cementum-enamel junction (CEJ) of the superior distal root of the first molar to the alveolar bone crest (ABC) were performed to assess bone loss.
Results
Diabetes resulted in significant bone loss and alterations in the number of cells that stained positive for inflammatory mediators. In the diabetic rats treated with green tea, we observed a decreased number of cells expressing RANKL and TNF-α compared with that observed in the diabetic rats treated with water. Additionally, green tea increased the numbers of cells that stained positive for OPG, RUNX-2 and IL-10 in the diabetic rats.