de Jesus Ferreira Marie Céleste, Crouzin Nadine, Barbanel Gérard, Cohen-Solal Catherine, Récasens Max, Vignes Michel, Guiramand Janique
Laboratory Cerebral Plasticity, FRE 2693 CNRS, University Montpellier II, 34095 Montpellier Cedex 05, France.
Free Radic Biol Med. 2005 Oct 15;39(8):1009-20. doi: 10.1016/j.freeradbiomed.2005.05.021.
Neuroprotection exerted by alpha-tocopherol against oxidative stress was investigated in cultured rat hippocampal neurons. In addition to its direct action as a radical scavenger revealed at concentrations above 10 microM, a transient application of 1 microM alpha-tocopherol phosphate (alpha-TP) to neurons induced a complete delayed long-lasting protection against oxidative insult elicited by exposure to Fe2+ ions, but not against excitotoxicity. A minimal 16-h application of alpha-TP was required to observe the protection against subsequent oxidative stress. This delayed protection could last up to a week after the application of alpha-TP, even when medium was changed after the alpha-TP treatment. Cycloheximide, added either 2 h before or together with alpha-TP, prevented the delayed neuroprotection, but not the acute. However, cycloheximide applied after the 16-h alpha-TP pretreatment did not alter the delayed neuroprotection. Neither Trolox, a cell-permeant analogue of alpha-tocopherol, nor other antioxidants, such as epigallocatechin-gallate and N-acetyl-L-cysteine, elicited a similar long-lasting protection. Only tert-butylhydroquinone could mimic the alpha-TP effect. Depletion of glutathione (GSH) by L-buthionine sulfoximine did not affect the delayed alpha-TP protection. Thus, in addition to its acute anti-radical action, alpha-TP induces a long-lasting protection of neurons against oxidative damage, via a genomic action on antioxidant defenses apparently unrelated to GSH biosynthesis.
在培养的大鼠海马神经元中研究了α-生育酚对氧化应激的神经保护作用。除了在浓度高于10微摩尔时作为自由基清除剂的直接作用外，向神经元短暂施加1微摩尔α-生育酚磷酸酯（α-TP）可诱导对暴露于Fe2+离子引起的氧化损伤的完全延迟持久保护，但对兴奋毒性无保护作用。观察到对随后氧化应激的保护作用需要至少16小时的α-TP施加。即使在α-TP处理后更换培养基，这种延迟保护在施加α-TP后仍可持续长达一周。在α-TP之前2小时添加或与α-TP一起添加的环己酰亚胺可阻止延迟的神经保护作用，但不能阻止急性神经保护作用。然而，在16小时的α-TP预处理后应用环己酰亚胺不会改变延迟的神经保护作用。α-生育酚的细胞渗透性类似物Trolox以及其他抗氧化剂，如表没食子儿茶素-3-没食子酸酯和N-乙酰-L-半胱氨酸，均未引起类似的持久保护作用。只有叔丁基对苯二酚可以模拟α-TP的作用。L-丁硫氨酸亚砜胺耗尽谷胱甘肽（GSH）并不影响α-TP的延迟保护作用。因此，除了其急性抗自由基作用外，α-TP还通过对明显与GSH生物合成无关的抗氧化防御的基因组作用，诱导神经元对氧化损伤的持久保护。
