RESUMO
OBJECTIVE: To investigate the role of parathyroid hormone related protein (PTHrP) in diabetic periodontitis. METHODS: After injected with 55mg/kg streptozotocin, diabetic rats were treated subcutaneously with low-dose (40µg/kg, once daily for 5days per week), middle-dose (80µg/kg) or high-dose (160µg/kg) PTHrP(1-34) peptide. Treatment continued for 12 weeks. Changes in periodontal tissues were confirmed by micro-computerized tomography assay and H&E analysis. We used tartrate resistant acid phosphatase (TRAP) staining to identify osteoclast cells. The expression of TNF-α, IL-1ß and IL-6 was assessed by immunohistochemistry and Western blot. RESULTS: Tooth-supporting structure loss was observed in periodontal tissues of diabetic rats. PTHrP (1-34) attenuated alveolar bone loss, especially in the middle-dose and high-dose group. Whereas TNF-α, IL-1ß and IL-6 protein levels were increased in the diabetic gingival tissues, PTHrP (1-34) treatment inhibited the increase of IL-1ß and IL-6, but had no effect on TNF-α. CONCLUSION: Type 1 diabetes increased the susceptibility to periodontal disease. Intermittent administration of PTHrP (1-34) exhibited an inhibitory effect on alveolar bone resorption and the gingival inflammation in periodontal tissues of diabetic rats.
