Role Of Nitric Oxide In Periodontitis On Spaugue Dewley Rats

Purpose: This experiment was designed to examine the possible role of nitricoxide (NO) on periodontitis in Spaugue Dawley rats.Methods: 120 rats were devided into fOur groups randomly. (l) control grouP; (2)periodofltitis + norma1 saline (P+NS): A model of periodontitis Which wasproduced in rat by a ligature of 2/0 braided silk placed around the cervix of thelower incisors. Then the rats were subected to intraPeritoneal injection of NS afteroperation everyday; (3) periodontitis + L-arginine (P+L-Arg): the rats weresubjected to intraperitoneal injection of L-Arg everyday after giving the sameoperation; (4) periodontitis + Aminoguanidine (P+AG): the rats were subected tointraperitoneal injection of AG everyday after giving the same operation. All the.rats were sacrificed at l,4,8 weeks, and the concentrations of NO were assayed byspectrophototometry; the gingival index (GI) and the attachment loss of theconnective tissue were measured using technology fOr image and graPhics..engineering research and the histopathologic changes of periodontium were alsoexamined under a light microscope.Results:(l) P+L-Arg group: l week, 4 weeks and 8 weeks after giving L-Arg, theconcentrations of NO significantIy increased, with significam difference comparedto the other groups; P+NS group: 4 weeks and 8 weeks after operation, theconcentrations of nitric oxide increased, with significant difference compared toP+AG group and the cofltroI.(2) 8 weeks after giving L-Arg, the connective tissue was dense1y infiltfated withinflammatory celIs, red blood cells and inflammatory cells immigrated into thepocket, collagen fibers edema, denature and the alveolar bone loss were observed,..demonstrating severe inflammatory responses in P+L-Arg group. Moderateinflammatory responses were observed in periodontium of the P+NS group. P+AGgroup showed a mi1d inflammatory.3(3) The gingival index increased gradual1y after operation, it raised more aftergiving L-Arg, and less after giving AG.(4) The attachment Ioss increased gradually after operation, it raised more aftergiving L-Arg, and less after giving AG.Conclusions:(1) As an important patho1ogical molecule, NO is, at least panly, involved in thedevelopment of experimental periodontitis in rats. The NO production waspositively associated with the seriousness of periodofltitis in this experimeflt.(2) Periodontitis as well as the damage of periodontal tissue were obviouslyaggravated by administration of L-Arg (substrate fOr nitric oxide production)indicated that NO could be a pathoIogicaI mediator in the process.(3) More importanly, administration of selective inhibitor of iNOS,...aminoguanidine, significantly alleviated the inflammation and the damage ofperiodontium imp1ying that NO produced by iNOS/NO pathWay play acritical role in the pathogenesis ofperiodontitis.(4) At last, the inhibition of iNOS may represent a poteniial theraPeulic strategyfOr the treatment of periodontitis.