铁离子沉积在急性CO中毒迟发性脑病白质脱髓鞘中的作用

The role of iron deposition on white matter demyelination in delayed encephalopathy after acute carbon monoxide poisoning

目的研究铁离子沉积在急性一氧化碳(CO)中毒迟发性脑病(DEACMP)大鼠脑白质脱髓鞘中的作用。方法将经Morris水迷宫实验筛选后的SD大鼠随机分成空气对照组(AC组)、CO中毒组(CO组)、去铁胺(DFO)+CO中毒组(DC组),各组内再分为1、3、7、14、21 d亚组。CO组和DC组采用腹腔注射CO气体法制备DEACMP模型,DC组大鼠于造模前1 h腹腔注射去铁胺100 mg/kg,造模后每天注射1次,AC组和CO组腹腔注射等量生理盐水。采用Morris水迷宫、HE染色观察大鼠染毒前后行为学改变和神经元细胞病理变化;普鲁士蓝染色检测铁离子表达;Western blot检测铁蛋白(Fn)、髓鞘碱性蛋白(MBP)的表达;免疫组化染色检测2',3'-环核苷酸磷酸二酯酶(CNPase)表达;免疫荧光染色检测MBP蛋白表达。结果染毒14 d后,CO组、DC组逃避潜伏期较AC组延长,DC组逃避潜伏期较CO组缩短,CO组穿越平台次数较AC组及DC组明显减少(P<0.05)。CO组于染毒14 d细胞变性、坏死明显;DC组细胞变性、坏死介于AC、CO组之间。CO组铁离子表达于14 d达峰值(P<0.05),与CO组比较,DC组铁离子、Fn表达减少,染毒3 d后DC组MBP表达增加,14 d和21 d时CNPase表达增多(P<0.05)。DC组较CO组髓鞘排列较密集,MBP表达增加。结论急性CO中毒后,过量沉积的铁离子可能通过减少CNPase和MBP的表达,损伤少突胶质细胞,导致大鼠脑白质进行性脱髓鞘,从而发生迟发性认知功能障碍。

Objective To investigate the role of iron deposition on white matter demyelination in rats with delayed encephalopathy after acute carbon monoxide(CO)poisoning(DEACMP).Methods SD rats screened by water maze experiment were divided into air control group(AC group),CO poisoning group(CO group)and deferriamine(DFO)+CO poisoning group(DC group).Each group was further divided into 5 subgroups including day 1,3,7,14 and 21 groups.The DEACMP model was prepared by intraperitoneal injection of CO gas in rats of CO group and DC group.Rats in DC group were intraperitoneally injected with 100 mg/kg of deferriamine 1 h before modeling,and injected once a day after modeling.Rats in AC and CO groups were intraperitoneally injected with the same amount of normal saline.Morris water maze and HE staining were used to observe the changes of the behavior and pathological neurons of rats before and after exposure.Prussian blue staining was used to detect the expression of iron.The expression of ferritin(Fn)and basic myelin protein(MBP)were detected by Western blot assay.The expression of 2',3'-cyclic nucleotide phosphodiesterase(CNPase)was detected by immunohistochemical staining and the expression of MBP was detected by immunofluorescence staining.Results After 14 days of exposure,the escape latencies were longer in CO and DC groups than those in AC group,and the escape latency was shorter in DC group than that in CO group.The times of crossing the platform were significantly lower in CO group than those in AC and DC groups(P<0.05).The cell degeneration and necrosis were found in CO group at 14 days after infection.The cell degeneration and necrosis in the DC group were between AC and CO groups(P<0.05).The expression of iron reached the peak on 14 days in CO group(P<0.05).Compared with CO group,the expressions of iron and Fn decreased in DC group,and the expression of MBP increased after 3 days of exposure in DC group,and the expressions of CNPase increased at 14 and 21 days(P<0.05).The myelin arrangement was denser in DC group than that in CO group,and the expression of MBP was increased.Conclusion After acute CO poisoning,excessive deposition of iron may lead to progressive demyelination of the white matter in rats by reducing the expressions of CNPase and MBP,and damaging oligodendrocytes(OLs),resulting in delayed cognitive dysfunction.