Low-level manganese exposure alters glutamate metabolism in GABAergic AF5 cells
Low-level manganese exposure alters glutamate metabolism in GABAergic AF5 cells
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DOI：
10.1016/j.neuro.2007.01.003
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发表时间：
2007-05-01
期刊：
影响因子：
3.4
通讯作者：
Smith, Donald R.
中科院分区：
文献类型：
--
作者：
Crooks, Daniel R.;Welch, Nicholas;Smith, Donald R.
最近的研究表明，苍白球可能是锰（Mn）的一个特别敏感的靶点，然而，Mn对gaba能神经元影响的体外研究由于缺乏表达gaba能特性的细胞模型而受到限制。在这里，我们研究了低水平Mn处理对细胞GABA和谷氨酸代谢的影响，使用新鉴定的AF5大鼠神经来源细胞系，该细胞系在体外培养过程中表现出GABA能特性。测定细胞内GABA和谷氨酸水平，测定GABA和谷氨酸向培养基的释放，测定培养基中谷氨酰胺的摄取，以及Mn对直接负责GABA合成和降解的酶、谷氨酸脱羧酶（GAD）和GABA转氨酶（GABA- t）的特异性影响。我们的研究结果表明，Mn对GAD和GABA-T的活性没有影响。同样，AF5培养物的低水平Mn处理对细胞内GABA水平只有很小的影响（为对照组的114%），对GABA的释放没有影响。相比之下，在Mn处理期间，细胞内和细胞外谷氨酰胺水平分别提高到对照组的170和198%，而细胞外谷氨酰胺水平下降到对照组的73%。总之，这些结果表明，在低水平Mn处理过程中，AF5细胞中的谷氨酸稳态可能优先受到影响，而不是GABA，这提示了Mn诱导的兴奋毒性可能产生的新机制。(c) 2007爱思唯尔公司版权所有。
Recent studies have suggested that the globus pallidus may be a particularly sensitive target of manganese (Mn), however, in vitro studies of the effects of Mn on GABAergic neurons have been restricted by the lack of a cell model expressing GABAergic properties. Here, we investigated the effects of low-level Mn treatment on cellular GABA and glutamate metabolism using the newly characterized AF5 rat neural-derived cell line, which displays GABAergic properties during culture in vitro. Intracellular GABA and glutamate levels were measured along with measurement of the release of GABA and glutamate into the culture medium, glutamine uptake from the culture medium, and the specific effects of Mn on the enzymes directly responsible for the synthesis and degradation of GABA, glutamate decarboxylase (GAD) and GABA transaminase (GABA-T). Our results demonstrate that Mn had no effect on the activities of GAD or GABA-T. Similarly, low-level Mn treatment of AF5 cultures had only a small effect on intracellular GABA levels (114% of control) and no effect on the release of GABA. In contrast, intracellular and extracellular glutamate levels were enhanced to 170 and 198% of control during Mn treatment, respectively, while extracellular glutamine decreased to 73% of controls. Together, these results suggest that glutamate homeostasis may be preferentially affected over GABA in AF5 cells during low-level Mn treatment, suggesting a novel mechanism by which Mn-induced excitotoxicity might arise. (c) 2007 Elsevier Inc. All rights reserved.