Differential Expression Of Histamine And Histamine Receptor 1in Rat Periodontitis

Backgrounds and objectives:Periodontitis, a kind of chronic infectious disease of periodontal tissue, is the first main cause of adult tooth loss in china. Dental plaque,the initiating factor of periodontitis, is an important factor of destroying the periodontal tissue. Under direct damage by pathogens and their products, as well as interactions among inflammatory mediators and immune cells, periodontal tissues were changed, which are characteristic by gingival inflammation, periodontal pocket formation, loose teeth, and loss of periodontal tissues. In this pathological process, a variety of inflammatory mediators released by various cells can cause and amplify immune injury in periodontal tissues. Histamine, an important chemical neurotransmitter presents in mast cell and basophil-granules without binding activity. Upon stimulation, histamine is released by degranulation and combines with histamine receptors, can regulate a variety of physiological and pathological processes by affecting a variety of cellular responses, especially playing an important role in inflammation and allergic reactions. This study is aimed at preliminarily investigating the role of histamine and histamine receptor 1 in periodontitis by establishing rat periodontitis model, observing the clinical periodontal indexes and the histological changes, detecting the levels of histamine in gingival crevicular fluid(GCF) by ELISA, H1 R mRNA expression in gingival tissues by real-time quantitative reverse transcription polymerase chain reaction(QT-PCR).Methods:1. Fourty adult Sprague Dawley( SD) rats were divided randomly into 2 groups: periodontitis rat model group and control group. We prepared the periodontitis models by ligating the right maxillary first molar by steel ligature combined with being raised by periodontitis diets.2. After 8 weeks, the clinical indexes were detected, including attachment loss(AL),plaque index(PLI) and gingival index(GI). HE staining was used to observe the pathological changes of rat periodontal tissues.3. The level of histamine in GCF were detected by ELISA.4. Histamine-receptor-1 mRNA expression in gingival tissue was detected by QT-PCR.Results:1. Weights of rats in the experimental group were slightly increased in 3 weeks, declined at 4 week, and gradually increased from 6 week. At 8 weeks, typical periodontitis was formed: periodontal pocket and AL were formed, probing depths(PD) were significantly increased, and junctional epithelium proliferated back to the root. There are significantly differences of clinical periodontal indexes between the periodontitis group and the control group(P<0.05).2. The levels of histamine in GCF in the periodontitis group were significant higher than in the control group( P < 0. 05).3. The levels of histamine-receptor-1 mRNA in the periodontitis group were obviously lower than in the control group( P < 0. 05).Conclusion:1. In our experiments, we successfully established the rat’s periodontitis model. The periodontal clinical situations and pathological changes in the periodontitis group represent the typically pathological changes of periodontitis.2. Upregulation of histamine and downregulation of histamine receptor 1 in the periodontitis group show that they may play important roles in the regulation of periodontitis.