OBJECTIVETo observe the effect of lipopolysaccharide(LPS) and interleukin-1beta (IL-1beta) on the expression of inducible nitric oxide synthase (iNOS) gene and nitric oxide (NO) in human periodontal ligament cells (hPDLCs).

METHODSAfter stimulating hPDLCs by LPS and IL-1beta, RT-PCR had been used to identify the expression of iNOS gene. The activity of iNOS in the culture was quantitated by enzyme-linked immune sorbent assay (ELISA). And the level of NO was determined by nitrate reductase method. RESULTS Slight amount of iNOS and NO had been detected in hPDLCs without sitimulation, but when stimulating with LPS and IL-1beta, the amount of the iNOS mRNA increased significantly in the cells in the time and dose dependent way (P<0.05). Under the stimulation with the same time or same dose, the productions of iNOS and NO stimulated by IL-1beta and in combination with LPS were larger than that stimulated with LPS (P<0.05).

CONCLUSIONThe expression NO and iNOS could be increased by stimulating hPDLCs with LPS and IL-1beta, which may contribute to the research on injecting LPS and IL-1beta at periodontal tissue of animal models.