RESUMEN
Objective:To study the effects of receptor activator of nuclear factor-kB ligand-RANKL in osteoblasts (OBs) activiated by Porphyromonas endodontalis(Pe),and to investigate the bone resorptive pathogenesis induced by Pe.Methods:Primary rat calvarial osteoblasts were cultured, then were infected with Pe ATCC 35406 at the density of 107 and 109 CFU/ml respectively for 24 h.To determine the kinetic effect of Pe on OBs,107 CFU/ml of Pe was used to stimulate the cells for 0,6,12,18 and 24 h respectively, RT-PCR were used to examine the RANKL mRNA expression.Results:The grey level ratio of RANKL mRNA expression to ?-actin in untreated OBs was 0.32,that in the cells infected by 107 and 109 CFU/ml of Pe for 24 h was increased to 1.73 and 2.24 respectively.Infected by 107 CFU/ml of Pe for 6,12 and 18 h,the ratio was 0.93,2.01 and 1.97 respectively.Conclusion:Pe may stimulate RANKL expresson in osteoblasts.