Manganese induces oxidative impairment in cultured rat astrocytes
Manganese induces oxidative impairment in cultured rat astrocytes
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DOI：
10.1093/toxsci/kfm095
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发表时间：
2007-07-01
影响因子：
3.8
通讯作者：
Aschner, Michael
中科院分区：
文献类型：
--
作者：
Milatovic, Dejan;Yin, Zhaobao;Aschner, Michael
过多的自由基形成被认为是与接触多种金属（包括锰 (Mn)）相关的神经毒性损伤的致病因素。众所周知，锰在星形胶质细胞中积累，影响其间接诱导和/或加剧神经元功能障碍的能力。本研究检查了锰治疗对原代星形胶质细胞培养物中以下终点的影响：（1）氧化损伤，（2）高能磷酸盐（5'-三磷酸腺苷，ATP）水平的改变，（3）线粒体内膜电位，以及（4）谷氨酰胺摄取和谷氨酰胺转运蛋白的表达。我们通过使用稳定同位素稀释方法测量 F-2-异前列腺素 (F-2-IsoPS)，然后采用气相色谱-质谱法和选择性离子监测来量化星形胶质细胞脑氧化损伤。我们的数据显示，接触 Mn（100 μM、500 μM 或 1 mM）后 2 小时，F-2-IsoPS 水平显着升高（p < 0.01）。与这一观察结果一致，Mn 诱导了 ATP 和线粒体内膜电位 (Delta Psi(m)) 的浓度依赖性降低，分别通过高压液相色谱法和电位染料四甲基罗丹明乙酯进行测量。此外，用Mn（100μM、500μM或1mM）预处理30分钟抑制了在1分钟和5分钟测量的谷氨酰胺（GLN）（H-3-谷氨酰胺）的净摄取。 100和500μM Mn处理24小时后，编码GLN转运蛋白SNAT3/SN1和SNAT1的信使RNA的表达受到抑制。我们的结果表明，星形胶质细胞中氧化应激的诱导、相关的线粒体功能障碍以及 GLN/谷氨酸循环的改变代表了锰发挥其神经毒性的关键机制。
Excessive free radical formation has been implicated as a causative factor in neurotoxic damage associated with exposures to a variety of metals, including manganese (Mn). It is well established that Mn accumulates in astrocytes, affecting their ability to indirectly induce and/or exacerbate neuronal dysfunction. The present study examined the effects of Mn treatment on the following endpoints in primary astrocyte cultures: (1) oxidative injury, (2) alterations in high-energy phosphate (adenosine 5'-triphosphate, ATP) levels, (3) mitochondrial inner membrane potential, and (4) glutamine uptake and the expression of glutamine transporters. We quantified astrocyte cerebral oxidative damage by measuring F-2-isoprostanes (F-2-IsoPS) using stable isotope dilution methods followed by gas chromatography-mass spectrometry with selective ion monitoring. Our data showed a significant (p < 0.01) elevation in F-2-IsoPS levels at 2 h following exposure to Mn (100 mu M, 500 mu M, or 1mM). Consistent with this observation, Mn induced a concentration-dependent reduction in ATP and the inner mitochondrial membrane potential (Delta Psi(m)), measured by the high pressure liquid chromatography method and the potentiometric dye, tetramethyl rhodamine ethyl ester, respectively. Moreover, 30 min of pretreatment with Mn (100 mu M, 500 mu M, or 1mM) inhibited the net uptake of glutamine (GLN) (H-3-glutamine) measured at 1 and 5 min. Expression of the messenger RNA coding the GLN transporters, SNAT3/SN1 and SNAT1, was inhibited after 100 and 500 mu M Mn treatment for 24 h. Our results demonstrate that induction of oxidative stress, associated mitochondrial dysfunction, and alterations in GLN/glutamate cycling in astrocytes represent key mechanisms by which Mn exerts its neurotoxicity.