核因子-κB和神经细胞黏附分子在急性一氧化碳中毒迟发性脑病大鼠海马的表达变化

Expression changes of nuclear factor-κB and nerve adhesion molecules in hippocampus of rats with delayed encephalopathy after acute carbon monoxide poisoning

目的探讨核因子-κB(nuclear factor-κB,NF-κB)和神经细胞黏附分子(nerve adhesion molecule,NCAM)的动态表达及突触重塑在急性一氧化碳中毒迟发性脑病(delayed encephalopathy after acute carbon monoxide poisoning,DEACMP)中的作用机制,并对干预效果进行评估。方法SD雄性大鼠120只,分为空气组(K组)、一氧化碳(CO)中毒组(C组)、CO中毒+毗咯烷二硫代氨基甲酸盐(PDTC)组(P组),再按第1、3、7、14、21天随机分为五个亚组,应用Morris水迷宫、海马组织HE染色及透射电镜观察大鼠行为、细胞及突触结构变化,采用Western blot、免疫荧光检测各组大鼠NF-κB、NCAM表达变化。结果C组大鼠于第14天后出现认知功能障碍,海马CA1区细胞坏死变性,海马组织中NF-κB表达呈持续性增长;P组大鼠NF-κB表达在第3天(IOD:6940.84±592.07)达到高峰后逐渐减少,且各时间点C组较K组、P组表达增多(P<0.05);C组、P组NCAM表达均在第3天(IOD:10712.49±1091.66、18020.52±1509.13)出现高峰后逐渐减少,且P组NCAM表达在各时间点均多于C组、K组(P<0.05);Western blot表达趋势与免疫荧光结果一致;电镜下C组与K组、P组比较,大鼠海马神经元突触前膜损伤,突触数量及突触小泡减少。结论CO中毒后可能通过上调NF-κB表达引起神经元细胞死亡、海马突触重塑;PDTC能够抑制NF-κB及促进NCAM的表达,起到保护神经元作用。

Objective To discuss the mechanism of action of the dynamic expression of nuclear factor-κB(NF-κB),neural cell adhesion molecule(NCAM)and synaptic remodeling in delayed encephalopathy after acutel carbon monoxide poisoning(DEACMP),and to evaluate the intervention effect.Methods 120 male Sprague-Dawley(SD)rats were divided into air group(K group),carbon monoxide(CO)poisoning group(C group)and CO poisoning + PDTC group(P group),the rats were randomly divided into five subgroups according to the first day,the third day,the seventh day,the fourteenth day and the twenty-first day.Morris water maze,HE staining of hippocampus anti electron microscopy were used to observe the changes of rat behaviour,cell and synaptic structure.The expression of NF-κB and NCAM in each group was detected by Western blot,immunofluorescence.Results In group C,cognitive dysfunction occurred after the fourteenth day,with necrosis and degeneration of hippocampal CAI cells and sustained increase of NF-κB expression in hippocampus.The expression of NF-κB in group P decreased gradually after reaching its peak on the third day(IOD:6940.84 ± 592.07),and the expression of NF-κB in group C was higher than that in group K and group P at each time point(P<0.05).The expression of NCAM in group C and P decreased gradually after the peak on the third day(IOD:10 712.49 ± 1091.66 vs.18 020.52 ± 1509.13),and the expression of NCAM in group P was more than that in group C and K at each time point,(P<0.05).The expression trend of Western blot was consistent with the results of immunofluorescence.Compared with groups K and P,the number of synapses and synaptic vesicles in hippocampal neurons in group C decreased with the damage of presynaptic membrane under electron microscope.Conclusion After CO poisoning,the neuronal cell death and hippocampal synaptic remodeling may be caused by up-regulating NF-κB expression.Pyrrolidinedithiocarbamate(PDTC)can inhibit NF-κB and promote NCAM expression,thus playing a role in protecting neurons.