| Inflammation and immunity responses of tissues and cells to external stimulation are regulated by a series of gene expressions. Transcription factors switch on or off the gene expression. Nuclear factor kappa B (NF- K B) which extensively exists in various tissues and cells, is an important protein molecule involved in gene transcription. After tissues or cells being stimulated by external factors, NF- K B in cytoplasm departs from the inhibitor protein I K B and is thus activated, then enters into nucleus binding to the special K B motif of target gene. Because expressions of many kinds of proteins including cytokines and inflammation medias are regulated by NF- K B and NF- K B exerts a pivot transcription control effects in inflammation and immunity responses. Therefore to block activation of NF- K B by applying antioxidant might be a new idea to deal with the inflammatory diseases. To investigate the mechanism of bacterial infection leading to a great amount of inflammatory release in the pulpal,-5-periapical and periodontal tissue has become one of the most challenging tasks of endodontics. The object of this study is to observe the change of NF- K B expression in experimental rat pulpitis, periapical periodontitis as well as that in human normal and inflammatory dental pulp, to investigate the activity alternation of NF- K B in cultured human pulp cells, periodontal cells and gingival cells which are stimulated by LPS and the effect of NF- K B inhibitor (antioxidant PDTC) on the release of IL-6 in human pulp cells and periodontal cells, in order to provide experimental bases for determining the mechanism by which NF- K. B regulates dental pulpal, periapical and periodontal inflammation.1. Expression of NF- K B in experimental rat pulpitisExperimental rat pulpitis model was established with opening medullary cavity. Immunohistochemical technique was applied to detect the expression of NF- K B hi pulpitis tissue at different phases. The results of staining showed that NF- K. B was present in cytoplasm with inactive style in normal rat pulp tissue. The expression area of NF- K B in experimental pulpitis model located mostly in the inflammatory area. Cytoplasm and nucleus of inflammatory cells contained a great mount of NF- K B in the inflammatory focus vicinal to the exposure point of pulp. Some tissues became necrosis, positive cells of NF- K. B expression extended from inflammatory core to the circumference and the number of positive cell and the amount of positive expression increased as inflammation developed. The staining of NF- K B in the vascular endothelial cells and the cells around the vessels appeared strongly positive. The temporal and spatial characteristics of NF- K B expression in the process of pulpal inflammation suggested that NF- K B always worked in the process of pulpal inflammation.?6-2. Expression of NF- K B in human normal and inflammatory pulp tissueImmunohistochemical study indicated that a few positive cells could be seen in normal human pulp tissue and positive cells were distributed in the inflammatory area, the vessels and macrophage. The area where NF- K B was positive is similar with that in rats inflammatory tissue but the degree of positive staining was weaker.3. Expression of NF- K B mRNA in experimental rats periapical periodontitis tissue.Animal model of experimental rats periapical periodontitis was established. Expression of NF- K. B mRNA in experimental rats periapical periodontitis tissue was detected by RT-PCR method. The results showed that NF- K B mRNA was at very low level in the control group and 3-day group, and it could be easily detected at 7 days of opening medullary cavity, with an obvious increase between the 7th and 14th day as the tissue got more inflamed and the expression began to decline at the 28th day in the periapical and periodontal inflammatory tissue.4. Changes of NF- * B activity in human dental pulp cell, periodontal ligament fibrocyte and gingival fibroblast when stimulated with endotoxin lipo...
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