An Experimental Study On Expression Of HSP27 And HSP70 In Rat Endotoxic Pulpitis

[AIM]: To establish a model of rat endotoxic pulpitis induced by Lipopolysaccharide(LPS);to study the dynamic expression and location of HSP27 and HSP70 in rat pulpitis model at different time;To evaluate the role of HSP27 and HSP70 on pulp injury and reparation in rat endotoxic pulpitis.[METHODS]: To establish Wistar rats endotoxic pupitis model by application of LPS:Thirty-two male, Wistar rats were used and divided equally into control and experimental groups.The animals in the experimental group were applied by LPS,whereas those in the control group received 0.9%NS.Four animals of each group were sacrificed at 1,3,5,7days,2,3,4,and5 weeks thereafter.The mandible of each animal was remove ,fixed, decalcified,embedded in paraffin, and setioned serially 5#m.The sections were stained with hematoxylin-eosin(HE).The slides were examined under a light microscope; To observe the dynamic expression and location of HSP27 and HSP70:The slides applied by LPS were examined immunohistochemically.HSP27 and HSP70 were detected with mouse HSP27 and HSP70 antibody by use of a UltraSensitiveS-P kit. The slides were examined under a light microscope.[RESULT]: PART ONE:It was about 5 weeks to observe the pulp histopathological changes. There was pulpal acute suppurative inflammation initially, than reparative dentin occurred; Up to 5 weeks, most part of pulps was necrosis. PART TWO: The acute pulpal inflammation was observed in 1day group and 2 days group. HSP70 was strongly positive in the pulpfibroblasts, endothelial and smooth muscle cells of vessel walls. Odontoblastwas moderately positive and became less gradually,and was weak positive in 2 weeks.There was a difference of staining between different parts of pulp tissue during the same period,and there was strongly positive in the pulp fibroblasts,endothelial and smooth muscle cells of vessel walls near part of injury during the early stage,and odontoblasts was moderately positive.The necrosis tissue was strongly positive even staining at the spot of injury .It changes gradually from the coronal pulp to the radicular pulp.After 2 weeks,odontoblast was still positive.PART THREE:The dental pulp displayed odontoblast lining up in a disorder,cell degenerating,cell infiltrating that most cell was neutrophil,capillary telangiectasia and hemorrhage during early pulpitis induced by LPS.There was an acute inflammation in 1day goup,and HSP27 displayed moderate positive staining in odontoblast,and was positive in fibroblast,smooth muscle and endothelial cells of vessel walls.HSP27 expressed less than before in 3 days,5 days and 7 days in odontoblast,fibroblast and endotheliaLAfter 2 weeks,there was still positive in odontoblast,odontoblastic process,fibroblast and reparative dentin.Up to 3 weeks and 4 weeks,there was weak positive in odontoblast,fibroblast and reparative dentin.[CONCLUSION]: The way to establish rat pulpitis induced by LPS was feasible ; HSP70 and HSP27can protect pulp cells,and inhibit developing of inflammation in early stage;HSP70 could take part in reparative dentin forming;HSP27 can play an important role in process of reparative dentin mineralization in later stage, and could be one of main cytokines.