Laboratory of Molecular Pharmacology, Division of Pharmaceutical Sciences, Kanazawa University Graduate School of Natural Science and Technology, Ishikawa, Japan.
J Pharmacol Sci. 2012;119(1):20-9. doi: 10.1254/jphs.12034fp. Epub 2012 Apr 18.
Necrotic damage leads to a massive leakage from injured cells of different intracellular constituents such as glutamate (Glu) and ATP, which are believed to play a role in the neuronal survival in the brain. In this study, we evaluated pharmacological properties of ATP, which is shown to be an endogenous inhibitor of N-methyl-D-aspartate (NMDA) receptors, on the neurotoxicity relevant to mitochondrial membrane potential disruption in cultured rat hippocampal neurons. Exposure to Glu or NMDA significantly inhibited cellular viability determined 24 and 48 h later, while simultaneous addition of 1 mM ATP significantly ameliorated the decreased viability in neurons exposed to Glu and NMDA, but not in those exposed to other cytotoxins. Both Glu and NMDA markedly increased intracellular free Ca(2+) levels in a manner sensitive to blockade by the exposure to ATP, but not by that to adenosine. Exposure to ATP significantly delayed the rate of mitochondrial membrane potential disruption induced by Glu and NMDA. These results suggest that extracellular ATP would play a role as an endogenous antagonist endowed to protect rat hippocampal neurons from the excitotoxicity mediated by NMDA receptors in association with the delayed mitochondrial membrane potential disruption after the liberation from adjacent cells under necrotic death.
细胞坏死会导致不同细胞内成分（如谷氨酸 (Glu) 和 ATP）从受损细胞中大量泄漏，这些成分被认为在大脑中神经元存活中发挥作用。在这项研究中，我们评估了 ATP 的药理学特性，ATP 被证明是 N-甲基-D-天冬氨酸 (NMDA) 受体的内源性抑制剂，对培养的大鼠海马神经元中线粒体膜电位破坏相关的神经毒性进行了评估。暴露于 Glu 或 NMDA 显著抑制了 24 和 48 小时后测定的细胞活力，而同时添加 1 mM ATP 可显著改善 Glu 和 NMDA 暴露的神经元活力下降，但对暴露于其他细胞毒素的神经元没有改善作用。Glu 和 NMDA 均显著增加细胞内游离 Ca(2+)水平，这种增加方式对 ATP 的暴露敏感，但对腺苷的暴露不敏感。暴露于 ATP 可显著延迟 Glu 和 NMDA 诱导的线粒体膜电位破坏的速率。这些结果表明，细胞外 ATP 可能作为一种内源性拮抗剂发挥作用，保护大鼠海马神经元免受 NMDA 受体介导的兴奋性毒性，以及在坏死死亡时从相邻细胞释放后延迟线粒体膜电位破坏。
