Limbrick D D, Churn S B, Sombati S, DeLorenzo R J
Department of Physiology, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298, USA.
Brain Res. 1995 Sep 4;690(2):145-56. doi: 10.1016/0006-8993(95)00552-2.
The hippocampus is especially vulnerable to excitotoxicity and delayed neuronal cell death. Chronic elevations in free intracellular calcium concentration ([Ca2+]i) following glutamate-induced excitotoxicity have been implicated in contributing to delayed neuronal cell death. However, no direct correlation between delayed cell death and prolonged increases in [Ca2+]i has been determined in mature hippocampal neurons in culture. This investigation was initiated to determine the statistical relationship between delayed neuronal cell death and prolonged increases in [Ca2+]i in mature hippocampal neurons in culture. Using indo-1 confocal fluorescence microscopy, we observed that glutamate induced a rapid increase in [Ca2+]i that persisted after the removal of glutamate. Following excitotoxic glutamate exposure, neurons exhibited prolonged increases in [Ca2+]i, and significant delayed neuronal cell death was observed. The N-methyl-D-aspartate (NMDA) channel antagonist MK-801 blocked the prolonged increases in [Ca2+]i and cell death. Depolarization of neurons with potassium chloride (KCl) resulted in increases in [Ca2+]i, but these increases were buffered immediately upon removal of the KCl, and no cell death occurred. Linear regression analysis revealed a strong correlation (R = 0.973) between glutamate-induced prolonged increases in [Ca2+]i and delayed cell death. These data suggest that excitotoxic glutamate exposure results in an NMDA-induced inability to restore resting [Ca2+]i (IRRC) that is a statistically significant indicator of delayed neuronal cell death.
海马体对兴奋性毒性和迟发性神经元细胞死亡尤为敏感。谷氨酸诱导的兴奋性毒性后细胞内游离钙浓度（[Ca2+]i）的慢性升高被认为与迟发性神经元细胞死亡有关。然而，在培养的成熟海马神经元中，尚未确定迟发性细胞死亡与[Ca2+]i的长期升高之间存在直接关联。启动本研究以确定培养的成熟海马神经元中迟发性神经元细胞死亡与[Ca2+]i的长期升高之间的统计关系。使用indo-1共聚焦荧光显微镜，我们观察到谷氨酸诱导[Ca2+]i迅速升高，在去除谷氨酸后仍持续存在。在兴奋性毒性谷氨酸暴露后，神经元表现出[Ca2+]i的长期升高，并观察到明显的迟发性神经元细胞死亡。N-甲基-D-天冬氨酸（NMDA）通道拮抗剂MK-801可阻断[Ca2+]i的长期升高和细胞死亡。用氯化钾（KCl）使神经元去极化导致[Ca2+]i升高，但在去除KCl后这些升高立即被缓冲，且未发生细胞死亡。线性回归分析显示谷氨酸诱导的[Ca2+]i长期升高与迟发性细胞死亡之间存在强相关性（R = 0.973）。这些数据表明，兴奋性毒性谷氨酸暴露导致NMDA诱导的无法恢复静息[Ca2+]i（IRRC），这是迟发性神经元细胞死亡的一个具有统计学意义的指标。
