The Changes Of IL-6, PGE₂ And NF-κB In Rats With Periodontitis Under The Condition Of Chronic Intermittent Hypoxia

Objective:Obstructive sleep apnea-hypopnea syndrome is a disease which involves varieties disciplines.Its main clinical manifestation is snoring which accompanies by apnea and shallow breath,recurrent hypoxemia,hypercapnia and sleep disorder structure,contributing to the daytime sleepiness, cardiovascular,pulmonary vascular complications and multiple organ damages.These features can affect patients’ living quality and lifetime.According the studies of abroad,the prevalence of OSAHS in adults is 2%-4%,and the disease is an independent risk factor for a variety of systemic disorders.Periodontitis is a infectious disease of periodontal tissue which is caused by plaque biofilm,contributing to the destruction of tooth-supporting structure,such as the formation of periodontal pocket,periodontal inflammation,progressive attachment loss and alveolar resorption.Periodontitis is the main cause of tooth loss.There are many reports which proved hypoxia would affect the structure and function of the periodontal ligament cell(PDLC) and aggravate the destruction of the periodontal tissue.Foreign scholars found that OSA is a risk factor for periodontitis,and OSAHS patients are more likely than controls to have a diagnosis of periodontitis.The purpose of the experiment is to establish the rat model of periodontitis under the condition of chronic intermittent hypoxia(CIH),and to analyse the correlation between CIH and periodontitis.Methods:1.To establish the periodontitis rat model under CIH:32 male 6-week-old SD rats were divided into 4 groups randomly,group A(normoxic control),group B(normoxic periodontitis),group C(CIH),group D(periodontitis+CIH).Ligation of the neck of the upper second molars by 0.20 mm orthodontic wire,feeding the high-glucose diet were performed to establish the group B and group D.The rats in the group C and group D were subjectedto intermittent hypoxia in a cycle of alternative nitrogen and oxygen in a closed chamber for 8 hours one day.The period of treatment is 8 weeks.2.The detection of oxygen concentration: Putting the oxygen recorder in the hypoxic chamber to test the oxygen concentration,The set of the chamber:the nitrogen was filled with 70 s,keeping the air hunger 25 s,the oxygen was filled with 25 s,in 2-minute cycle.3.Stereologic procedures:The examiner completed an assessment of periodontal conditions after the rats were anesthetized,using the probe.Recording the probing depth(PD)and sulcus bleeding index(SBI).4.Blood sampling and histological examination:After the treatment procedures,all rats were anesthetized by i.p. and blood samples were collected from abdominal. The maxillas collected from rats after treatment,and the maxillas were carried out decalcification,dehy-drated,embedded in paraffin,and sectioned along the second molars in a buccolingual plane for hematoxylin-eosin, and then collecting images.5.ELISA detection and immunohistochemistry analyses: PGE2 and IL-6 production from serum was determined by ELISA,periodonal tissue for the immunohistochemistry todetect NF-κB.Results:1.Behavioral Changes:When the rats in the group C and D were subjected to the hypoxic chamber,the rats showed excited behavior,then showed accelerated and deepened breathing,obvious abdominal breathing,slow moving, with time goes by.2.Stereologic results:The rats in group B and D expressed the freatures of periodontitis.The rats in group A and C didn’t express the manifestations of periodontitis.The results of PD and SBI in group B,C,D were higher than that in group A(P<0.05),and in group D were the highest(P<0.05).3.Histologic findings:The structure of the periodontium was normal in group A and C,bone resorption was not obvious.In group B and D,there was obvious connective tissue attachment loss and alveolar bone loss.4.ELISA results:The contents of IL-6 and PGE2 in group B,C,D were higher than that in group A(P<0.05),and in group D were the highest(P<0.05).5. Immunohistochemical staining: The group A was weak positive staining,group B,C,D were strong positive staining. The AOD of NF-κB in group B,C,D were higher than that in group A(P<0.05),and in group D were the highest(P<0.05).Conclusions:1.The rat model with periodontitis under the condition of chronic intermittent hypoxia was successfully established.2.The serum levels of IL-6 and PGE2 can be elevated in rats with periodontitis. In CIH the serum levels of IL-6 and PGE2 are higher, the destruction of periodontal tissue is promoted futher. The serum level of inflammatory facors, PD and SBI change consistently,which can reflect the changes of periodontitis in CIH.3.The expression of NF-κB in periodontal tissue are increased by CIH. The activated NF-κB in gingival tissue is highest in group D. Excessive activation of NF-κB may be involved in the development of periodontal diseases under CIH condition.4.The condition of CIH can aggravate the inflammation of periodontitis. It reminds that there is correlation between CIH and periodontitis.