Raymond L A, Moshaver A, Tingley W G, Huganir R L
Kinsmen Laboratory of Neurological Research, Department of Psychiatry, University of British Columbia, Vancouver, Canada.
Mol Cell Neurosci. 1996 Feb;7(2):102-15. doi: 10.1006/mcne.1996.0008.
Excessive activation of glutamate receptors is thought to play a critical role in neuronal excitotoxicity. To compare the cytotoxic potential of different glutamate receptor subtypes and correlate receptor biophysical properties with cytotoxicity, we have expressed recombinant receptors in human embryonic kidney 293 (HEK-293) cells. Survival of transfected cells was analyzed under conditions of defined agonist concentration and exposure time. For HEK-293 cells transfected with N-methyl-D-aspartate (NMDA) receptors, the EC50 for NMDA-induced cytotoxicity was 300 microM. Experiments using ion substitution, or cells expressing mutant NMDA receptors with low calcium permeability, suggested that both calcium and sodium influx through NMDA receptors contributed to cytotoxicity. In contrast, cytotoxicity was not observed in cells transfected with calcium permeable alpha-amino 3-hydroxy-5-methyl-4-isoxazole propionate- or kainate-type glutamate receptors even at saturating agonist concentrations, unless inhibitors of agonist-dependent desensitization were included. These results directly demonstrate that calcium permeability and desensitization kinetics play important roles in determining the excitotoxic potential of different glutamate receptor subtypes.
谷氨酸受体的过度激活被认为在神经元兴奋性毒性中起关键作用。为了比较不同谷氨酸受体亚型的细胞毒性潜力，并将受体生物物理特性与细胞毒性相关联，我们已在人胚肾293（HEK - 293）细胞中表达了重组受体。在确定的激动剂浓度和暴露时间条件下分析转染细胞的存活率。对于用N - 甲基 - D - 天冬氨酸（NMDA）受体转染的HEK - 293细胞，NMDA诱导细胞毒性的EC50为300微摩尔。使用离子替代或表达低钙通透性突变型NMDA受体的细胞进行的实验表明，通过NMDA受体的钙内流和钠内流均导致细胞毒性。相比之下，在用钙通透性α - 氨基 - 3 - 羟基 - 5 - 甲基 - 4 - 异恶唑丙酸或海人藻酸型谷氨酸受体转染的细胞中，即使在饱和激动剂浓度下也未观察到细胞毒性，除非包括激动剂依赖性脱敏抑制剂。这些结果直接表明，钙通透性和脱敏动力学在确定不同谷氨酸受体亚型的兴奋性毒性潜力中起重要作用。
