title: Parathyroid hormone administration may modulate periodontal tissue levels of interleukin-6, matrix metalloproteinase-2 and matrix metalloproteinase-9 in experimental periodontitis.
abstract: 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.
  
  
  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-1 beta, 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 < 0.01) and of MMP-2 in the T15 and T30 groups (p < 0.05). Zymography assays demonstrated that treatment with parathyroid hormone led to a decrease in MMP-9 activity (p < 0.01). TRAP staining of alveolar bone revealed that osteoclasts were present in higher numbers (p < 0.05) in the groups not treated with parathyroid hormone.
  
  
  CONCLUSIONS
  These data suggest that intermittent administration of parathyroid hormone can down-regulate the expression of biomarkers responsible for connective tissue breakdown and bone resorption, and potentially affect alveolar bone resorption activity.
authors.affiliation: School of Dentistry at Piracicaba, Division of Histology, Department of Morphology, University of Campinas, Sao Paulo, Brazil.
authors.forename: M R
authors.initials: MR
authors.lastname: Marques
authors.forename: M C L G
authors.initials: MC
authors.lastname: dos Santos
authors.forename: A F
authors.initials: AF
authors.lastname: da Silva
authors.forename: F H
authors.initials: FH
authors.lastname: Nociti
authors.forename: S P
authors.initials: SP
authors.lastname: Barros
mesh_terms: D000135:Acid Phosphatase / Q000032:analysis; D016301:Alveolar Bone Loss / Q000473:pathology / Q000517:prevention & control; D000539:Alveolar Process / Q000473:pathology; D000818:Animals; D015415:Biomarkers / Q000032:analysis; D002452:Cell Count; D003238:Connective Tissue / Q000187:drug effects / Q000473:pathology; D004195:Disease Models, Animal; D015536:Down-Regulation; D005881:Gingiva / Q000187:drug effects / Q000473:pathology; D007279:Injections, Subcutaneous; D053583:Interleukin-1beta / Q000032:analysis / Q000187:drug effects; D015850:Interleukin-6 / Q000032:analysis*; D007527:Isoenzymes / Q000032:analysis; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000032:analysis / Q000187:drug effects*; D020780:Matrix Metalloproteinase 9 / Q000032:analysis / Q000187:drug effects*; D010010:Osteoclasts / Q000473:pathology; D010281:Parathyroid Hormone / Q000008:administration & dosage / Q000627:therapeutic use*; D010518:Periodontitis / Q000473:pathology / Q000517:prevention & control*; D012333:RNA, Messenger / Q000032:analysis / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D000071681:Tartrate-Resistant Acid Phosphatase; D013997:Time Factors
chemical_list: D015415:Biomarkers; D053583:Interleukin-1beta; D015850:Interleukin-6; D007527:Isoenzymes; D010281:Parathyroid Hormone; D012333:RNA, Messenger; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase; D020778:Matrix Metalloproteinase 2; C522363:Mmp2 protein, rat; D020780:Matrix Metalloproteinase 9