【摘要】 目的研究血红素加氧酶-1系统(HO-1)对急性一氧化碳中毒大鼠脑海马损伤的保护作用及其机制。方法随机将90只大鼠分为4组,即空气对照组、急性一氧化碳(CO)染毒组、氯化高铁血红素(Hemin)+CO组、锡原卟啉(SnPP)+CO组,每组15~25只大鼠。采用Western blot法和免疫组化法测定HO-1蛋白的表达情况;测定各组大鼠脑水肿程度及大鼠24 h死亡率,脑海马丙二醛(MDA)浓度和caspase-3蛋白表达及活性水平变化;以HE染色观察脑海马神经元病理形态学改变及损伤程度。结果急性CO中毒组大鼠脑海马出现严重损伤,表现为染毒24 h后海马组织含水量为88.9%,死亡率为25%,海马MDA浓度4.23 nmol/mg,海马caspase-3活性(光密度值:4.67)和蛋白表达均显著升高,和空气对照组相比差异有统计学意义(P<0.01);病理学检测结果亦显示海马CA1区锥体细胞发生坏死,与对照组比较细胞密度降低44%。给予Hemin预处理能诱导大鼠海马HO-1高表达,并对海马损伤产生明显的保护作用,表现为Hemin预处理大鼠海马组织含水量降低,为84.2%;24 h死亡率降低为5%,海马MDA浓度为2.5 nmol/mg,caspase-3活性(光密度值:2.18)和蛋白表达明显低于CO染毒组。此外,Hemin预处理亦使染毒大鼠的病理学指标得到明显改善,海马CA1区锥体细胞坏死数目显著减少。HO活性抑制剂SnPP可部分阻断上述保护性作用,表现为SnPP预处理后CO染毒大鼠海马组织水肿程度加重(海马含水量为91.2%),24 h死亡率增加(30%),氧化损伤加重,海马CA1区锥体细胞出现明显水肿和坏死。结论HO-1诱导表达对急性CO中毒引起的大鼠脑海马损伤有明显的保护作用,提示HO-1系统在防护急性CO中毒海马损伤的病理过程中占有重要地位;HO-1的保护机制可能与其减轻脂质过氧化反应,抑制caspase-3蛋白表达和活性对抗细胞凋亡有关。更多还原

【Abstract】 Objectives To explore the functional roles of HO-1 induction in a rat model of CO-exposed hippocampal injury.Methods Experimental animal groups were as follows:(1)CO exposure group(n=15),(2)Control group(n=25),Hemin+CO exposure(n=25),and SnPP+CO exposure(n=25).And the survival rates at 24 h,hippocampal water content,levels of malondialdehyde(MDA),levels of pro-apoptotic caspase-3 and the expression of HO-1 in hippocampus were measured with rats in four groups after acute CO poisoning.Results Acute CO exposure produces severe hippocampal injury in rats.However,hemin pretreatment reduced both the CO-induced rise in hippocampal water content(88.9%)and levels of neuronal damage in the hippocampus(neuron densities were reduced by 44% in animals treated with CO);hemin pretreatment reduced both the CO-induced rise in hippocampal water content(84.2%)and levels of neuronal damage in the hippocampus;survival rates at 24 h(95%)were significantly improved.Upregulation of HO-1 by hemin pretreatment resulted in a significant decrease in hippocampal levels of malondialdehyde(MDA),a marker of oxidative stress(MDA levels is 2.5 nmol/mg);levels of pro-apoptotic caspase-3 were also reduced(optical density value is 2.18).In contrast,inhibition of HO activity by administration of tin protoporphyrin IX(SnPP,a specific inhibitor of HO)abolished the neuroprotective effects of HO-1 induction.Conclusion These results showed that the upregulation of endogenous HO-1 expression therefore plays a pivotal protective role in CO neurotoxicity,and the protection seemed to be mediated through the anti-oxidant and anti-apoptotic functions.更多还原