Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS 90035003, Brazil.
Brain Res. 2012 Oct 10;1478:74-82. doi: 10.1016/j.brainres.2012.08.039. Epub 2012 Aug 29.
Short/branched chain acyl-CoA dehydrogenase (SBCAD) deficiency is an autosomal recessive disorder of isoleucine metabolism biochemically characterized by accumulation of 2-methylbutyrylglycine (2MBG) and 2-methylbutyric acid (2MB). Affected patients present predominantly neurological symptoms, whose pathophysiology is not yet established. In the present study, we investigated the in vitro effects of 2MBG and 2MB on important parameters of oxidative stress in cerebral cortex of young rats and C6 glioma cells. 2MBG increased thiobarbituric acid-reactive species (TBA-RS), indicating an increase of lipid oxidation. 2MBG induced sulfhydryl oxidation in cortical supernatants and decreased glutathione (GSH) in these brain preparations, as well as in C6 cells, indicating a reduction of nonenzymatic brain antioxidant defenses. In contrast, 2MB did not alter any of these parameters and 2MBG and 2MB did not affect carbonyl formation (protein damage). In addition, 2MBG-induced increase of TBA-RS levels and decrease of GSH were prevented by free radical scavengers, implying that reactive species were involved in these effects. Furthermore, the decrease of GSH levels caused by 2MBG was not due to a direct oxidative action since this metabolite did not alter sulfhydryl content from a commercial solution of GSH. Nitric oxide production was not altered by 2MBG and 2MB, suggesting that reactive oxygen species possibly underlie 2MBG effects. Finally, we verified that 2MBG did not induce cell death in C6 cells. The present data show that 2MBG induces lipid oxidative damage and reduces the antioxidant defenses in rat brain. Therefore, it may be postulated that oxidative stress induced by 2MBG is involved, at least in part, in the pathophysiology of the brain damage found in SBCAD deficiency.
短链/支链酰基辅酶 A 脱氢酶 (SBCAD) 缺乏症是一种常染色体隐性遗传疾病，其异亮氨酸代谢的生化特征是 2-甲基丁酰甘氨酸 (2MBG) 和 2-甲基丁酸 (2MB) 的积累。受影响的患者主要表现为神经症状，但其病理生理学尚未确定。在本研究中，我们研究了 2MBG 和 2MB 在幼年大鼠大脑皮质和 C6 神经胶质瘤细胞中重要氧化应激参数的体外效应。2MBG 增加了硫代巴比妥酸反应性物质 (TBA-RS)，表明脂质氧化增加。2MBG 诱导皮质上清液中的巯基氧化，并降低这些脑制剂以及 C6 细胞中的谷胱甘肽 (GSH)，表明非酶脑抗氧化防御减少。相比之下，2MB 没有改变这些参数中的任何一个，并且 2MBG 和 2MB 没有影响羰基形成 (蛋白质损伤)。此外，自由基清除剂可预防 2MBG 诱导的 TBA-RS 水平升高和 GSH 降低，这表明活性物质参与了这些作用。此外，2MBG 引起的 GSH 水平降低不是由于直接的氧化作用，因为这种代谢物不会改变商业 GSH 溶液中的巯基含量。2MBG 和 2MB 没有改变一氧化氮的产生，表明活性氧可能是 2MBG 作用的基础。最后，我们验证了 2MBG 不会诱导 C6 细胞死亡。本研究数据表明，2MBG 诱导大鼠大脑脂质氧化损伤并降低抗氧化防御。因此，可以假设 2MBG 诱导的氧化应激至少部分参与了 SBCAD 缺乏症中发现的脑损伤的病理生理学。
