Parathyroid hormone administration may modulate periodontal tissue levels of interleukin-6, matrix metalloproteinase-2 and matrix metalloproteinase-9 in experimental periodontitis

Background and Objective: Intermittent administration of the parathyroid hormone (1–34) has an anabolic effect on bone and it has been shown to reduce alveolar bone loss in experimental periodontitis models. The aim of the present study was to investigate the effect of parathyroid hormone on tissue degradation‐related factors in an experimental periodontitis model in rats. Material and Methods: Periodontitis was induced in seventy‐six male Wistar rats using ligature around the lower right first molars. The animals were then treated with parathyroid hormone (1–34) (T‐group) or vehicle (C‐group), three times a week for 15 d (C15, T15) or 30 d (C30, T30). At each experimental time‐point, the 19 rats were killed in each group and the gingival tissue around the first lower molar was removed and prepared for the following analyses: mRNA expression of interleukin‐1beta, interleukin‐6, matrix metalloproteinase (MMP)‐2 and MMP‐9, and gelatinolytic activity of MMP‐2 and MMP‐9. Hemimandibles were decalcified, and serial sections were processed and analyzed for interleukin‐6 immohistochemistry. Samples were also histochemically stained by tartrate‐resistant acid phosphatase (TRAP) to evaluate the number of osteoclasts present. Results: Parathyroid hormone‐treated samples showed decreased of levels of mRNA for interleukin‐6 in the T30 group (p