Methods: The root canals of the first molars from 192 C57BL/6 mice were inoculated with 10μl of LPS from E. coli (1 mg/ml). After 7, 14, 21 and 28 days the animals were euthanized and tissues were removed for gene evaluation by qRT-PCR. Values of mRNA relative expression were compared by two way-ANOVA followed by Bonferroni post-test (α = 0.05).
Results: Inoculation of LPS into the root canals induced expression of COX-2 gene, along with up-regulation of mRNA for RANK, RANKL, and OPG. The administration of Indomethacin inhibited the expression of mRNA for RANK and RANKL and stimulated OPG expression. The use of Celecoxib led to an up-regulation of RANK and RANKL mRNA in all periods without OPG regulation, compared to the control group. Several growth factors, cell differentiation, cellular adhesion, molecules and transcription factors were expressed during 7 and 14 days of apical periodontitis development. Of note, after administration of Celecoxib or Indomethacin, expression was increased to Bmpr1b, Bmp3, Bmp4, Tgfbr1, Col10a1, Col14a1, Col12a1, Col16a1, Col17a1, Itga2, Itga2b, Itgam, Comp and Msx1. On the other hand some genes were downregulated including Bmp2, Tgfb1, Tgfb2, Tgfbr3, Col1a1, Col4a2, Col5a1, Col6a1, Icam1, Scarb1, Cd36, Cdh11, Vcam1, Runx2 and Sox9.
Conclusion: Indomethacin differently from Celecoxib treatment inhibited signaling for osteoclastogenesis, suggesting that mediators derived from arachidonic acid metabolism might be either positive or negative regulators of periapical bone loss.
FAPESP: 2010/17611-4 and 2012/08421-2