胆碱能抗炎通路在右美托咪定防治脓毒症小鼠谵妄中的作用

Dexmedetomidine attenuates pyohemia-associated delirium in mice through the cholinergic anti-inflammatory pathway

目的 观察胆碱能抗炎通路在右美托咪定防治脓毒症小鼠谵妄发生中的作用.方法将小鼠随机分为5组：生理盐水对照组（C组）、右美托咪定对照组（DEX组）、脓毒症组（LPS组）、右美托咪定保护组（LPS＋DEX组）、α-银环蛇毒素组（α-BGT组）.每组均分为2个亚组（n=6）.亚组1行旷场实验;亚组2行新物体识别实验,实验后处死小鼠并留取标本.透射电镜观察小鼠海马结构改变,用酶联免疫吸附试验（ELISA）法检测炎性因子水平.结果 C组和DEX组各项指标比较差异均无统计学意义.LPS、α-BGT组出现了明显谵妄症状,而LPS＋DEX组症状较轻.（1）旷场试验结果显示,制模前各组旷场实验观察指标均无差异.制模24h后,与C组比较,LPS组小鼠表现为对新环境的认知、学习和记忆能力均下降,紧张度增加;右美托咪定可明显改善小鼠上述对新环境的探索、习惯和情绪变化,但α-BGT可拮抗右美托咪定的保护作用.（2）新物体识别实验结果显示,与C组比较,LPS组探究新事物的能力下降;右美托咪定可改善小鼠的探究能力,而α-BGT可拮抗右美托咪定的保护作用.（3）ELISA结果显示,LPS组血清及海马组织TNF-α和IL-1β水平较C组明显升高[血清（ng/L）TNF-α：794.80±93.99比23.60±3.03,IL-1β：148.49±24.80比64.55±5.13,海马组织[pg/（mg·prot）TNF-α：176.14±11.25比6.71±0.49,IL-1β：50.61±5.86比16.73±1.15,P=0.000],右美托咪定可改善LPS诱导的血清及海马组织TNF-α和IL-1β水平升高[血清（ng/L）TNF-α：184.44±26.58比794.80±93.99,IL-1β：77.43±10.75比148.49±24.80,海马组织（pg/mg·prot）TNF-α：64.83±13.09比176.14±11.25,IL-1β：17.97±2.26比50.61±5.86,P=0.000],而α-BGT可拮抗右美托咪定的保护作用[血清（ng/L）TNF-α：812.31±86.25比184.44±26.58,IL-1β：156.42±17.94比77.43±10.75,海马组织（pg/mg·prot）TNF-α：181.94±8.69比64.83±13.09,IL-1β：52.10±5.59比17.97±2.26,P=0.000].LPS＋DEX组较LPS组及α-BGT组海马病理学改变明显较轻.结论 右美托咪定通过激活胆碱能抗炎通路减轻全身及脑组织的炎性反应,从而改善小鼠的谵妄状态.

Objective To study if the protective effect of dexmedetomidine on the pyohemia-associated delirium is through the cholinergic anti-inflammatory pathway.Methods Sixty male adult C57 mice were randomly divided into five groups （n=12 each）： saline group （group C）,dexmedetomidine （DEX） alone group （group DEX）,endotoxemia （LPS） group （group LPS）,dexmedetomidine protection group （group LPS＋DEX） and alpha-bungarotoxin （α-BGT） group （group α-BGT）.Each group were assigned to two subunits （n=6 each）,mice in subunit one were sacrificed after examining the open field test,mice in subunit two were sacrificed after testing the novel object recognition.The level of inflammatory factors were measured by enzyme-linked immune sorbent assay （ELISA）.The ultrastructure changes of the hippocampus in mice were observed by transmission electron microscopy.Results Compared with group C,there are no significant differences in group DEX.Dexmedetomidine significantly attenuated the delirious syndrome after LPS induced endotoxemia,however,the effect of dexmedetomidine disappeared in group α-BGT,and the syndrome of cognitive dysfunction in LPS group were more severe than that in group α-BGT.（1） The open field test show that there are no significant differences each group with that before model establishment;after the models were established 24 h,compared with group C,group LPS show that the abilities of cognition to new environment、learning and memory were decreasing,the tension is increasing.preemptive administration of dexmedetomidine significantly attenuated the delirious syndrome after LPS induced endotoxemia;however,preemptive administration of dexmedetomidine failed to control the delirious syndrome in group α-BGT.（2） The novel object recognition testshow that compared to group C,the ability of exploring the novel object is decreasing;preemptive administration of dexmedetomidine significantly improve the exploration ability,however,preemptive administration of dexmedetomidine failed to control the delirious syndrome in group α-BGT.（3） The results of ELISA show that： Compared with group C,the concentrations of tumor necrosis factor-α （TNF-α） and interleukin （IL）-1β in serum and Hippocampus were all increased in LPS groups[Serum （ng/L） TNF-α： 794.80±93.99 vs.23.60±3.03,IL-1β： 148.49±24.80 vs.64.55±5.13,Hippocampus （pg/mg·prot） TNF-α： 176.14±11.25 vs.6.71±0.49,IL-1β： 50.61±5.86 vs.16.73±1.15,P=0.000],compared with group LPS,the concentrations were all significantly decreased in group LPS＋DEX[Serum （ng/L） TNF-α： 184.44±26.58 vs.794.80±93.99,IL-1β： 77.43±10.75 vs.148.49±24.80,Hippocampus （pg/mg·prot） TNF-α： 64.83±13.09 vs.176.14±11.25,IL-1β： 17.97±2.26 vs.50.61±5.86,P=0.000].However,α-BGT can reverse the protective effect[Serum （ng/L）： TNF-α： 812.31±86.25 vs.184.44±26.58,IL-1β： 156.42±17.94 vs.77.43±10.75,Hippocampus （pg/mg·prot） TNF-α： 181.94±8.69 vs.64.83±13.09,IL-1β： 52.10±5.59 vs.17.97±2.26,P=0.000].TEM shown that the histopathological damage of hippocampus tissue in group LPS and α-BGT were heavier,which in group LPS＋DEX was reversed partially.Conclusion Central alpha-2 agonist dexmedetomidine attenuates sepsis-associated delirium syndrome likely through activating cholinergic anti-inflammatory pathway and inhibiting the inflammatory responses in serum and brain.