The Mechanism Of Dysfunction Of Inflammation-Resolving Pathways In Early Postoperative Cognitive Dysfunction In Elderly Mice

Background:Postoperative cognitive dysfunction(POCD)refers to a perioperative reversible mental disorder,such as cognitive dysfunction,memory impairment,anxiety,personality changes,and mental confusion.POCD increases the likelihood of postoperative complications and the risk for postoperative mortality.Numerous epidemiological studies indicate that POCD is most common among elderly patients over 65 years old.Previous research indicates that the development of postoperative cognitive decline(POCD)is associated with central nervous system inflammation cascade caused by sterile surgical trauma.The effects of various inflammatory factors have been confirmed in in vitro animal experiments,and these inflammatory factors damage neurons collectively.Among the elderly,the expression levels of inflammatory factors and inflammatory cells in the central nervous system are high,and inflammatory reactions are easily induced under stress,which impairs cognitive function.Varieties of organs and tissues are involved in maintaining normal immune function in body,of which the spleen plays a vital role.The function of the spleen plays an important role in the pathogenesis of some neuropathy diseases through multiple channels,the most concerned one is the cholinergic anti-inflammatory pathway(CAP).The vagus nerve activates the α7 nicotinic acetylcholine receptor(nAChR),which reduces the synthesis of pro-inflammatory cytokines by inhibiting nuclear factor-κB(NF-κB)activity,which is the mechanism of action of the cholinergic anti-inflammatory pathway.Compared with humoral regulation,the CAP responds more rapidly and directly.The importance of CAP in resolving neuro-inflammatory and cognitive decline caused by sterile trauma has been well established.Objectives:1.Explore the differences in the occurrence and development of cognitive dysfunction in elderly mice and adult mice by constructing a mouse tibial fracture model.2.Research around the cholinergic anti-inflammatory pathway,using a combination of in vivo and in vitro experiments,to futher explore the postoperative cognition of the cholinergic anti-inflammatory pathway through the changes and differences in the expression levels of inflammation-related factors in mice.Status and role in the development of dysfunction.3.This experiment reveals the possible molecular mechanism of postoperative cognitive dysfunction in elderly mice,provides new perspectives for exploring this mechanism,and provides new treatment ideas and preventive measures for postoperative cognitive dysfunction in medical practice.Strategy.Methods:1.Tibial fracture model in mice:48 female C57BL/6J mice,weighing 35 to 40 g,12 to 4 weeks of age in the adult group and 8 to 9 months of age in the elderly group,randomly divided into:adult control group(AM Sham)The adult surgery group(AM Surgery),the elderly control group(EM Sham),the elderly surgery group(EM Surgery),the elderly surgery+agonist group(EM-P Surgery),the surgery group of mice were treated with tibial fractures,the control group Mice were anesthetized only.2.Behavioral analysis:The fear condition tracking test(TFC)was used to evaluate the cognitive level of mice in each group.3.ELISA:used to detect the expression levels of inflammatory factors:TNF-α,IL-6 and IL-10 in the peripheral blood of mice in each group.4.RT-PCR:used to detect the expression levels of inflammatory factors:TNF-α,IL-6 and IL-10 in the hippocampus of each group of mice.5.Immunofluorescence:used to detect the expression and distribution of inflammatory cells M2 macrophages in the hippocampus of each group of mice.6.Flow cytometry:used to detect the expression of CD11b/c+α7 nAChR+cells in the spleen of each group of mice.7.Statistical analysis:use the SPSS 22.0 software for statistical analysis,and the results were expressed as mean ± standard deviation(x±SD).P<0.05 was considered statistically significant.Results:1.TFC results showed that compared with adult mice,elderly mice were more likely to develop cognitive dysfunction after surgery.2.ELISA and RT-PCR results showed that the expression levels of pro-inflammatory factors TNF-α and IL-6 in peripheral blood and hippocampus of elderly mice were higher than that of adult mice,and the expression of anti-inflammatory factor IL-6 Levels are lower than in adult mice,and PUN can reverse this trend.3.The results of immunofluorescence showed that the expression level of M2 macrophages in hippocampus of elderly mice was higher than that of adult mice.PUN could reverse this trend.4.The results of flow cytometry showed that the expression of CD11b/c+α7 nAChR+cells in the spleen of elderly mice was significantly higher than that of adult mice.Conclusion:1.Older mice are more susceptible to POCD than adult mice.2.Prone to POCD in elderly mice is related to cholinergic anti-inflammatory pathway disorders in vivo.3.Intraperitoneal injection of PUN can enhance the role of cholinergic anti-inflammatory pathway in elderly mice,and then alleviate the decline of cognitive function in elderly mice to some extent.