高压氧对缺氧缺血性脑损伤新生大鼠神经细胞凋亡以及凋亡诱导因子核转移的抑制作用

Effect of hyperbaric oxygenation on translocation of apoptosis-inducing factor from mitochondria to nucleus and neuronal apoptosis in neonatal rat with hypoxia ischemia brain damage.

【目的】探讨高压氧(hyperbaric oxygen,HBO)对缺氧缺血性脑损伤(hypoxia-ischemia brain damage,HIBD)新生大鼠神经细胞凋亡以及凋亡诱导因子(apoptosis-inducing factor,AIF)核转移的影响,以揭示HBO治疗的分子机制。【方法】42只7日龄SD大鼠随机分为假手术组、HIBD组和HBO干预组。HBO干预组在HIBD后2 h给予单次HBO治疗(2.5ATA,1.5 h)。然后于规定时间点取脑进行Nissl染色、TUNEL染色进行皮质区、海马CA1区以及丘脑区凋亡神经细胞定量分析,并用免疫组织化学方法检测AIF核转移的情况。【结果】在HIBD后48 h皮质区、海马CA1区神经元有明显丢失,而HBO干预组相应脑区的神经元丢失不明显。HIBD后12、24、48 h皮质区和海马CA1区TUNEL阳性细胞数随时间逐渐增加;HBO干预组两个脑区在不同的时间点TUNEL阳性细胞数均比HIBD组减少,其中两组在24 h和48 h时差异有显著性(P<0.05)。HBO干预组各观察脑区在不同的时间点AIF阳性细胞数均明显减少,与HIBD组相比差异均有显著性(P<0.05)。【结论】单次HBO(100%,2.5ATA)治疗可以有效抑制HIBD后神经细胞的凋亡。可能的机制是抑制HIBD后AIF的核转移以阻断其介导的非Caspase依赖性的神经细胞凋亡。

[Objective] To investigate the effect of hyperbaric oxygenation （HBO） on translocation of Apoptosis-inducing factor （AIF） from mitochondria to nucleus and neuronal apoptosis in neonatal rat with hypoxia ischemia brain damage（HIBD）. [Methods] Forty-twor healthy seven-day-old SD rats pups were used as research subjects and randomly divided into three groups： （1） sham-operated group （ SHAM, n = 6 ） ; （2） HIBD group （ HIBD, n = 18） ; （3） HIBD＋HBO group （ HIBD＋HBO,n = 18）. The brain were removed and analyzed at various time after HIBD 12 h, 24 h,and 48h. Single HBO therapy （2.5 atmospheres absolute, ATA for 1.5 h） was used in this study. [Results] The result of Nissl staining showed more neuronal loss in the hippocampus CA1 region and cortex appeared at 48 h after hypoxia-ischemia, HBO treatment partially prevented neuronal cell loss at the time point. TUNEL staining revealed morphologic apoptotic changes at 12 h,24 h,48h after HIBD, the number of TUNEL-positive cells were a time-dependent increase in the hippocampus CA1 region and cortex. After HBO treatment, the number of TUNEL-positive cells observed in the hippocampus CA1 region and cortex had decreased dramatically at both 24 h and 48 h （compared with HIBD group,P〈0.05）. The number of AIF-positive cells observed in the hippocampus CA1 region and cortex were increased in all time points. After HBO treatment, the AIF immunoreactivity was weakened at all regions in all time points. The number of AIF-positive cells was also significantly decreased in the hippocampus CA1 region and cortex at all time points（compared with HIBD group,P〈0.05）. [Conelusions] Single hyperbaric oxygen（100% oxygen,2.5ATA,1.5 h） offers its neuroprotection by reducing hypoxiaischemia-induced apoptosis. The possible mechanism mey be inhibiting the translocation of AIF, which can induce apoptosis in a non-Caspase-dependent cell death,from mitochondria to nucleus.