Effect of L-NAME on alveolar bone loss in rats

Objectives: The role of nitric oxide (NO) in the pathogenesis of periodontitis and diabetes has not been fully elucidated. The aim of this study was to evaluate the effects of L-NAME in the expression of iNOS on alveolar bone loss in diabetic and non-diabetic periodontitis rats. Methods: One hundred and ninety-two rats were divided into groups of 24 animals each with water intake (W) or L-NAME intake (L): 1) group C-W, control group; 2) group C-L, control group; 3) group D-W, diabetic (streptozotocin-STZ), unligated rats ; 4) group D-L, diabetic (streptozotocin-STZ), unligated rats; 5) group P-W, chronic periodontitis rats, induced by dental ligature; 6) group P-L, chronic periodontitis rats, induced by dental ligature; 7) group DP-W, diabetic chronic periodontitis rats; and 8) group DP-L, diabetic chronic periodontitis rats. The sacrifices were performed at 3, 7, 15 and 30 days after ligature-induced periodontitis to assess radiographic findings and iNOS inhibition in gingival tissues. Gingival tissues were submitted to RNA extraction and complementary DNA (cDNA) was synthetized by reverse transcription and submitted to Real-time PCR. Results: Groups with D-W or P-W and DP-W showed significantly higher iNOS expression compared to L-NAME groups in all periods. L-NAME treatment (L) significantly decreased iNOS expression in all groups with inflammatory pathological conditions (p < 0.05). Conclusions: The L-NAME treatments lead to a decrease NOS levels and a consequent reduction on alveolar bone loss in rats with experimental periodontitis induced by dental ligature alone and in association with diabetics. Grant: FAPESP 2005/58624-3