Zhang S, Kashii S, Yasuyoshi H, Honda Y, Ujihara H, Sasa M, Tamura Y, Akaike A
Department of Ophthalmology and Visual Sciences, Graduate School of Medicine, Kyoto University, Japan.
Graefes Arch Clin Exp Ophthalmol. 2000 Mar;238(3):243-8. doi: 10.1007/s004170050351.
Both in vivo and in vitro studies suggest that excess stimulation of non-NMDA receptors can result in massive neuronal death in the retina. In particular, murine amacrine neurons have been known to show marked susceptibility to the toxic effects of kainate.
This study was designed to examine and characterize the role of N-methyl-D-aspartate (NMDA) receptor vs non-NMDA receptor in glutamate-induced neurotoxicity in the retina.
Primary cultures obtained from fetal rat retina (gestation day 16-19) were used for the experiment. The neurotoxicity was assessed quantitatively using the trypan blue exclusion method. Electrophysiological studies using patch-clamp techniques were performed to record whole-cell currents evoked by these excitatory amino acids.
Removal of extracellular Ca2+ from the medium or application of MK-801 reduced the extent of cell death induced by the brief exposure to glutamate, NMDA, and kainate. By contrast, cell death induced by a 60-min exposure to kainate was not affected by MK-801. The electrophysiological study demonstrated that MK-801 abolished the whole-cell currents evoked by NMDA but had no effect on those induced by kainate or AMPA.
These findings demonstrate that brief exposure to kainate induces cell death by way of activating NMDA receptors in cultured fetal retinal neurons and that NMDA receptors are the predominant route of fetal retinal neurotoxicity induced by brief glutamate exposure.
体内和体外研究均表明，非NMDA受体的过度刺激可导致视网膜中大量神经元死亡。特别是，已知鼠无长突神经元对海人酸的毒性作用表现出明显的易感性。
本研究旨在检测和表征N-甲基-D-天冬氨酸（NMDA）受体与非NMDA受体在谷氨酸诱导的视网膜神经毒性中的作用。
实验使用从胎鼠视网膜（妊娠第16 - 19天）获得的原代培养物。使用台盼蓝排斥法对神经毒性进行定量评估。采用膜片钳技术进行电生理研究，以记录这些兴奋性氨基酸诱发的全细胞电流。
从培养基中去除细胞外Ca2+或应用MK-801可降低短暂暴露于谷氨酸、NMDA和海人酸所诱导的细胞死亡程度。相比之下，MK-801对60分钟暴露于海人酸所诱导的细胞死亡没有影响。电生理研究表明，MK-801消除了NMDA诱发的全细胞电流，但对海人酸或AMPA诱发的电流没有影响。
这些发现表明，短暂暴露于海人酸通过激活培养的胎鼠视网膜神经元中的NMDA受体诱导细胞死亡，并且NMDA受体是短暂谷氨酸暴露诱导胎鼠视网膜神经毒性的主要途径。
