Chronic ethanol exposure causes mitochondrial dysfunction and oxidative stress in immature central nervous system neurons
Chronic ethanol exposure causes mitochondrial dysfunction and oxidative stress in immature central nervous system neurons
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DOI：
10.1007/s00401-007-0199-4
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发表时间：
2007-06-01
影响因子：
12.7
通讯作者：
de la Monte, Suzanne M.
中科院分区：
文献类型：
--
作者：
Chu, Jennifer;Tong, Ming;de la Monte, Suzanne M.
实验性胎儿酒精综合症（FAS）中的小脑发育不全与胰岛素刺激的生存信号受损有关。体外研究表明，乙醇对神经元存活的抑制是通过细胞凋亡和线粒体功能障碍介导的。由于胰岛素和胰岛素样生长因子（IGF）调节能量代谢，而乙醇可以通过对DNA和蛋白质造成氧化损伤来发挥其毒性作用，因此我们进一步表征了妊娠期长期接触乙醇对线粒体基因表达的影响，以及乙醇对线粒体功能的抑制是由胰岛素/IGF反应性受损介导的。从妊娠第 6 天到分娩，怀孕的 Long-Evans 大鼠被喂食含有 0、2、4.5、6.5 或 9.25% v/v 乙醇的等热量液体饮食。检查出生后第 1 天收获的小脑的氧化应激指数以及线粒体、促氧化和促凋亡基因表达的 mRNA 水平。大鼠原代小脑神经元培养物用于表征乙醇（50 mM，96 小时）对胰岛素和 IGF 刺激的线粒体功能和 ATP 产生的影响。暴露于乙醇的小脑显着降低了编码复合物 II-A、IV 和 V 的线粒体基因的 mRNA 水平，增加了 p53 和 NADPH 氧化酶 (NOX) 1 和 3 的表达，并增加了小脑颗粒细胞中 4-羟基-2,3-壬烯醛 (HNE) 和 8-OHdG 的免疫反应性。暴露于含 6.5% 或 9.25% 乙醇饮食的幼鼠小脑中 p53 和 NOX 基因的激活最高，而线粒体复合物 IV 和 V 表达的损伤在低水平和高水平乙醇暴露下相似。体外实验证实，乙醇处理会降低编码复合物 IV 和 V 的线粒体基因的神经元表达，损害线粒体功能和 ATP 产生，并增加 HNE 和 8-OHdG 免疫反应性，但他们也表明这些作用不依赖于胰岛素或 IGF。总之，结果表明 FAS 中的线粒体功能障碍、氧化应激和 DNA 损伤可能很大程度上是由于乙醇的毒性作用，而不是胰岛素或 IGF 信号传导的特定损伤。
Cerebellar hypoplasia in experimental fetal alcohol syndrome ( FAS) is associated with impaired insulin-stimulated survival signaling. In vitro studies demonstrated that ethanol inhibition of neuronal survival is mediated by apoptosis and mitochondrial dysfunction. Since insulin and insulin-like growth factors (IGFs) regulate energy metabolism, and ethanol can exert its toxic effects by causing oxidative damage to DNA and proteins, we further characterized the effects of chronic gestational exposure to ethanol on mitochondrial gene expression, and the degree to which ethanol inhibition of mitochondrial function is mediated by impaired insulin/IGF responsiveness. Pregnant Long-Evans rats were fed isocaloric liquid diets containing 0, 2, 4.5, 6.5, or 9.25% v/v ethanol from gestation day 6 through delivery. Cerebella harvested on postnatal day 1 were examined for indices of oxidative stress, and mRNA levels of mitochondrial, pro-oxidant, and pro-apoptosis gene expression. Rat primary cerebellar neuron cultures were used to characterize the effects of ethanol ( 50 mM for 96 h) on insulin and IGF stimulated mitochondrial function and ATP production. Ethanol-exposed cerebella had signifcantly reduced mRNA levels of mitochondrial genes encoding Complexes II-A, IV, and V, increased expression of p53 and NADPH oxidase ( NOX) 1 and 3, and increased immunoreactivity for 4-hydroxy-2,3-nonenal (HNE) and 8-OHdG in cerebellar granule cells. The activations of p53 and NOX genes were highest in cerebella from pups exposed to the 6.5 or 9.25% ethanol containing diet, whereas the impairments in mitochondrial Complex IV and V expression were similar at low and high levels of ethanol exposure. In vitro experiments confirmed that ethanol treatment reduces neuronal expression of mitochondrial genes encoding Complexes IV and V, impairs mitochondrial function and ATP production, and increases HNE and 8-OHdG immunoreactivity, but they also showed that these effects were not insulin- or IGF-dependent. Together, the results suggest that mitochondrial dysfunction, oxidative stress, and DNA damage in FAS may be largely due to the toxic effects of ethanol rather than specific impairments in insulin or IGF signaling.