Intermittent administration of parathyroid hormone ameliorated alveolar bone loss in experimental periodontitis in streptozotocin-induced diabetic rats

- Ligature applying could induce periodontitis and streptozocin (STZ) injection would aggravate manifestations of the induced periodontitis.
- Parathyroid Hormone (PTH) intermittent administration could not only reduce alveolar bone loss induced by periodontitis in diabetic rats, but also improve its micro-architecture.
- PTH intermittent administration in a short time reduces alveolar bone loss by increasing osteoblastic activity and moderately decreasing osteoclastic activity.
- PTH intermittent administration could reduce inflammatory cell infiltration , which contributed to reduced alveolar bone loss.
- PTH intermittent administration could slightly decrease RANKL/OPG ratio. The slight decreased ratio of RANKL/OPG and reduced inflammatory cell infiltration contributed to decreasing osteoclastic activity. The increased osteoblastic activity and moderately decreased osteoclastic activity induced by PTH intermittent administration contribute to the manifestation improvement of periodontitis in diabetic rats.

ObjectiveIntermittent administration of parathyroid hormone (PTH) has been demonstrated to have anabolic effects on bone metabolism and is approved for use in the treatment of osteoporosis. This study evaluates the role of intermittent PTH administration on alveolar bone loss in streptozotocin (STZ)-induced diabetic rats.DesignFifty male Sprague Dawley rats were randomly divided into the following five groups: (1) a control group (saline placebo without ligature and STZ injection), (2) a PTH group (PTH administration without ligature and STZ injection), (3) an L group (saline placebo with ligature), (4) an L + STZ group (saline placebo with ligature and STZ injection), and (5) an L + STZ + PTH group (PTH administration with ligature and STZ injection). PTH was administered at 75 μg/kg per dose four times a week for 28 days. Subsequently, all rats were sacrificed, and their mandibles were extracted for micro-computed tomography (micro-CT) scanning, as well as histological and immunochemical evaluation.ResultsMicro-CT scanning demonstrated the anabolic effect of PTH on alveolar bone metabolism in STZ-induced diabetic rats (P < 0.05), and histomorphometry indicated that PTH inhibited inflammation of the periodontium and increased the level of osteoblastic activity (P < 0.05). Immunochemical evaluation showed that rats subjected to both ligature placement and STZ injection had the highest receptor activator of nuclear factor kappa B ligand (RANKL)/osteoprotegerin (OPG) ratio and that PTH administration decreased this ratio.ConclusionIntermittent systemic PTH administration effectively reduced alveolar bone loss and ameliorated the manifestation of experimental periodontitis in STZ-induced diabetic rats.