Change of nitric oxide concentration in ligature-induced periodontitis in rats

AIM: To study the possible role of nitric oxide (NO) in the development of periodontitis and the relationship between the NO concentration and the attachment loss. METHODS: Seventy-two Sprague-Dawley rats were randomly assigned to two groups, the control group and periodontitis group. Experimental periodontitis in rats was produced by a ligature of braided silk. The nitric oxide concentration was indirectly ascertained by the concentration of nitrite (NO2-) and nitrate (NO3-) in the gingival tissue, which was assayed by spectrophotometry. The attachment loss (AL) was measured by the technology of the cellular graphics engineering research. The histopathologic change in periodontium was observed under a light microscope by using the histotomy. RESULTS: Compared to control group, the NO2-/NO3- concentration in gingival tissue was significantly higher in periodontitis group at four weeks and eight weeks following ligation (P<0.01). In periodontitis group, the NO2-/NO3- concentration in gingival tissue was higher at eight weeks than that at four weeks following ligation (P<0.01). At four weeks and eight weeks, the AL in experimental periodontitis in rats was significantly increased than that at one week after ligation (P<0.01); and the AL was also much higher at eight weeks than that at four weeks (P<0.01). CONCLUSIONS: The NO2-/NO3- concentration in the gingival tissue in periodontitis group was significantly higher than that in control group. These results demonstrate that the NO2-/NO3- concentration is related to the severity of AL, and NO synthesis is very important to the process of inflammation and lesion in periodontium. Reducing NO production may be of great therapeutic value in the treatment of periodontitis.