Investigation of the role of cyclooxygenase-2 in periapical bone resorption induced by bacterial lipopolysaccharide

Abstract

During the inflammatory response, several mediators are released locally with order to stimulate the humoral and cellular immune response. Through the action of the enzyme cyclooxygenase-2 structural changes occur in the chain of arachidonic acid leading to the synthesis of prostaglandins responsible for regulating the potential bone metabolism during inflammatory events. Thus, the objective of this study will evaluate the role of the enzyme cyclooxygenase-2 in bone resorption and periapicalexpression of genes involved in bone metabolism, after inoculation of bacterial lipopolysaccharide(LPS) in the root canals of molars of mice. One hundred and twenty C57BL/6 mice will be used. Root canals will be inoculated with a solution containing bacterial lipopolysaccharide from E. coli (1.0 mg / ml). After experimental periods of 7, 14, 21 and 28 days, the animals will undergo euthanasia and the blocks containing teeth and bone will be removed for histology and RNA extraction. Histological sections will be made, stained with hematoxylin and eosin, and for immunohistochemistry for COX-2, RANK, RANKL and OPG and analyzed by conventional light microscopy and fluorescence. Then gene expression will be assessed by real time reverse transcription polymerase chain reaction (qRT-PCR) using the TaqMan ® system and by means of a PCR Array (Osteogenesis RT PCR² Profiler Array. Data obtained will be statistically analyzed according to the data distribution.