Kane Cynthia J M, Chang Jason Y, Roberson Paula K, Garg Tarun K, Han Lihong
Department of Neurobiology and Developmental Sciences, College of Medicine, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA.
Alcohol. 2008 Feb;42(1):29-36. doi: 10.1016/j.alcohol.2007.10.003.
Oxidative stress is a candidate mechanism for ethanol neuropathology in fetal alcohol spectrum disorders. Oxidative stress often involves production of reactive oxygen species (ROS), deterioration of the mitochondrial membrane potential (MMP), and cell death. Previous studies have produced conflicting results regarding the role of oxidative stress and the benefit of antioxidants in ethanol neuropathology in the developing brain. This study investigated the hypothesis that ethanol neurotoxicity involves production of ROS with negative downstream consequences for MMP and neuron survival. This was modeled in neonatal rats at postnatal day 4 (P4) and P14. It is well established that granule neurons in the rat cerebellar cortex are more vulnerable to ethanol neurotoxicity on P4 than at later ages. Thus, it was hypothesized that ethanol produces more oxidative stress and its negative consequences on P4 than on P14. A novel experimental approach was used in which ethanol was administered to animals in vivo (gavage 6g/kg), granule neurons were isolated 2-24h post-treatment, and ROS production and relative MMP were immediately assessed in the viable cells. Cells were also placed in culture and survival was measured 24h later. The results revealed that ethanol did not induce granule cells to produce ROS, cause deterioration of neuronal MMP, or cause neuron death when compared to vehicle controls. Further, granule neurons from neither P4 nor P14 animals mounted an oxidative response to ethanol. These findings do not support the hypothesis that oxidative stress is obligate to granule neuron death after ethanol exposure in the neonatal rat brain. Other investigators have reached a similar conclusion using either brain homogenates or cell cultures. In this context, it is likely that oxidative stress is not the sole and perhaps not the principal mechanism of ethanol neurotoxicity for cerebellar granule neurons during this stage of brain development.
氧化应激是胎儿酒精谱系障碍中乙醇神经病理学的一种潜在机制。氧化应激通常涉及活性氧（ROS）的产生、线粒体膜电位（MMP）的恶化以及细胞死亡。先前的研究在发育中大脑的乙醇神经病理学中，关于氧化应激的作用和抗氧化剂的益处产生了相互矛盾的结果。本研究调查了乙醇神经毒性涉及ROS产生并对MMP和神经元存活产生负面下游影响的假说。这在出生后第4天（P4）和第14天（P14）的新生大鼠中进行了模拟。众所周知，大鼠小脑皮质中的颗粒神经元在P4时比在更晚的年龄更容易受到乙醇神经毒性的影响。因此，有人推测乙醇在P4时比在P14时产生更多的氧化应激及其负面后果。采用了一种新的实验方法，即对动物进行体内乙醇给药（灌胃6g/kg），在治疗后2 - 24小时分离颗粒神经元，并立即在活细胞中评估ROS产生和相对MMP。细胞也被置于培养中，并在24小时后测量存活率。结果显示，与溶剂对照组相比，乙醇并未诱导颗粒细胞产生ROS、导致神经元MMP恶化或导致神经元死亡。此外，来自P4和P14动物的颗粒神经元对乙醇均未产生氧化反应。这些发现不支持氧化应激是新生大鼠脑内乙醇暴露后颗粒神经元死亡所必需的这一假说。其他研究人员使用脑匀浆或细胞培养也得出了类似的结论。在这种情况下，氧化应激很可能不是大脑发育这一阶段小脑颗粒神经元乙醇神经毒性的唯一机制，也许也不是主要机制。
