Study On The Relationship Between Periodontitis And Cognitive Dysfunction

Background and purpose: Periodontitis is a chronic infectious disease caused by plaque microorganisms which leads to the damage of periodontal support tissues.It is the most important cause of tooth loss in our country.Studies have shown that there is a relationship between periodontitis and multiple other systemic diseases.With the accelerated aging of the population,cognitive dysfunctional diseases such as senile dementia have become more and more harmful to human health.Clinical manifestations include progressive cognitive impairment and mental disorders.In previous studies,the correlation between periodontitis and cognitive disorders focused on epidemiological investigations but lacked experimental research.Therefore,this study was to initially explore the possible relationship between periodontitis and cognitive dysfunction through experimental studies.Methods:In Part I,the experiment investigated the effect of P.gingivalis-derived lipopolysaccharide(P.gingivalis-LPS)on cognitive dysfunction in C57 BL / 6 mice.Mice were injected with P.gingivalis-LPS with or without Toll-like receptor 4(TLR4)inhibitor(TAK-242).Behavioral experiments,immunohistochemistry,RT-PCR,ELISA and Western blot were used to evaluate cognitive function and related signaling pathways.In Part II,we established the model of periodontitis in SD rats and assessed the effect of periodontitis on cognitive function.The periodontitis model was detected by Micro-CT and HE staining.The effect of periodontitis on cognitive function in rats was assessed by behavioral experiments.The changes of microglia and astrocytes in cortex and hippocampus were illustrated by immunohistochemistry.Results: In Part I,the results showed that P.gingivalis-LPS significantly impaired the ability of spatial learning and memory in mice as well as passive avoidance of response memory ability.Microglia and astrocytes were activated in the brain,inflammatory cytokines were elevated,and with the TLR4/NF-κB signaling pathway was activated.In Part II,the results showed that periodontitis significantly impaired the ability of spatial learning and memory in rats.Microglia and astrocytes were activated in the cortex and hippocampus.Conclusions: Periodontal pathogenic factors might lead to cognitive dysfunction,and neuroinflammation plays an important role in cognitive dysfunction.