Involvement of calcium ion in apoptosis induced by NMDA antagonists and ethanol

NMDA受体和受体相关离子通道被认为在皮层和海马神经元的谷氨酸兴奋毒性中起主要作用。NMDA受体拮抗剂（NK 801、APV）和乙醇可抑制培养的皮层神经元的NMDA神经毒性。然而，已知NMDA拮抗剂和乙醇对某些神经元群体有毒。在本研究中，我们研究了是否NMDA拮抗剂和乙醇诱导神经细胞凋亡的培养条件。将大鼠皮质培养物（体外10天）暴露于MK 801（1 nM至10 μM）和乙醇（50至300 mM）24至48小时，导致细胞凋亡，呈剂量依赖性。NMDA（25和50 μM）可减弱MK 801和乙醇诱导的细胞死亡。MK 801和乙醇降低细胞内钙离子浓度。caspase-3的激活伴随着MK 801和乙醇诱导的细胞死亡，呈剂量依赖性。此外，放线菌酮（0.1和0.2 μg/ml）保护细胞免受MK 801和乙醇诱导的细胞死亡和caspase-3激活。胰岛素样生长因子1（5 - 20 ng/ml）也抑制MK 801和乙醇诱导的细胞死亡和caspase-3活化。NR 2B选择性NMDA拮抗剂艾芬地尔也诱导凋亡性细胞死亡和caspase-3激活。这些结果表明，在神经元发育过程中，NMDA受体的适度激活可能支持神经元的存活，抑制NMDA受体的药物可能诱导神经元凋亡。

The NMDA receptor and receptor-associated ion channel are assumed to play a principal role in glutamate excitotoxicity on neurons of the cortex and hippocampus. NMDA antagonists (NK801, APV) and ethanol inhibit the NMDA neurotoxicity in cultured cortical neurons. However, NMDA antagonists and ethanol are known to be toxic to certain neuronal populations. In the present study, we have examined whether NMDA antagonists and ethanol induce neuronal apoptosis in a culture condition. Exposure of rat cortical cultures (10 days in vitro) to MK801 (1 nM to 10 μM ) and ethanol (50 to 300 mM) for 24 to 48 hr resulted in apoptotic cell death in a dose-dependent manner. NMDA (25 and 50 μM) attenuated the MK801-and ethanol-induced cell death. MK801 and ethanol decreased intracellular calcium ion concentrations. Activation of caspase-3 was accompanied by MK801-and ethanol-induced cell death in a dose-dependent manner. Further, cycloheximide (0.1 and 0.2 μg/ml) protected the cells from MK801 and ethanol-induced cell death and caspase-3 activation. Insulin-like growth factor 1 (5 to 20 ng/ml) also inhibited the cell death and caspase-3 activation induced by MK801 and ethanol. Ifenprodil, a NR2B-selective NMDA antagonist, also induced apoptotic cell death and caspase-3 activation. These results indicate that the moderate NMDA receptor activation may support the survival of neurons during the neuronal development, and drugs which inhibit NMDA receptor may induce apoptosis.