兴奋毒作用下皮层神经细胞Ca^2＋变化机制

目的：检测谷氨酸兴奋毒损伤时，有胞外有Ca^2 或无Ca^2 ,，或有尼莫地平和Ca^2 条件下，神经细胞内(Ca^2 )]i的变化，方法：用Fura-2/AM体外检测新生大鼠皮层神经细胞内游离钙离子浓度的方法。结果：发现谷氨酸兴奋毒可使皮层神经细胞Ca^2 ]i上升并有剂量依赖性，胞外无Ca^2 或加入尼莫地平时神经细胞Ca^2 ]i虽也上升，但幅度降低。三种条件下神经细胞在兴奋毒作用下Ca^2=]i变化各不相同。结论：表明谷氨酸活化神经细胞膜上受体，使胞内钙库动员和细胞膜Ca^2 通道开放，导致Ca^2_]i在短时间内总体表现为持续上升，存在兴奋毒损伤过程中有膦脂酶A2活化过度参与的信使基础。

Change of the Ca2+ density in the cortical neurons after excitotoxicity

Objective To investigate the change of the neuron intracellular Ca~(2 ) density after excitotoxicity. Methods Fresh cortical neurons were isolated from new-born rats. Before and after t he Glutamic acid excitotoxicity, the intracellular Ca~(2 ) density were deter mined by fura-2 fluorometry under different conditions: extracellular Ca~(2 ) exist or not exist, or both extracellular Ca~(2 ) and nimodipine exist. Results Glutamic acid excitotoxicity significantly increased the neuron intracellular Ca~(2 ) density and has a dose-dependent manner. The ef fect was especially obvious under the extracellular Ca~(2 )exist condition. Conclusions Our results suggest that Glutamic acid might stimul ate intracellular Ca~(2 ) stores and Ca~(2 ) channels in the membrane by a ctivating its receptor on the neuronal membrane, so that the intracellular Ca 2 ) rise in a short time and phospholipase A2 activation would be involved in the process.