Resumo

BEZERRA, M.M.; BRITO, G.A.C.; RIBEIRO, R.A.  e  ROCHA, F.A.C.. Low-dose doxycycline prevents inflammatory bone resorption in rats. Braz J Med Biol Res [online]. 2002, vol.35, n.5, pp. 613-616. ISSN 1414-431X.  http://dx.doi.org/10.1590/S0100-879X2002000500015.

Matrix metalloproteinases (MMP) are considered to be key initiators of collagen degradation, thus contributing to bone resorption in inflammatory diseases. We determined whether subantimicrobial doses of doxycycline (DX) (£10 mg kg^-1 day^-1), a known MMP inhibitor, could inhibit bone resorption in an experimental periodontitis model. Thirty male Wistar rats (180-200 g) were subjected to placement of a nylon thread ligature around the maxillary molars and sacrificed after 7 days. Alveolar bone loss (ABL) was measured macroscopically in one hemiarcade and the contralateral hemiarcade was processed for histopathologic analysis. Groups of six animals each were treated with DX (2.5, 5 or 10 mg kg^-1 day^-1, sc, 7 days) and compared to nontreated (NT) rats. NT rats displayed significant ABL, severe mononuclear cell influx and increase in osteoclast numbers, which were significantly reduced by 5 or 10 mg kg^-1 day^-1 DX. These data show that DX inhibits inflammatory bone resorption in a manner that is independent of its antimicrobial properties.

Palavras-chave : Tetracyclines; Doxycycline; Metalloproteinases; Periodontitis; Osteoporosis; Bone resorption; Inflammation.