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拮抗剂（NK801， APV）和乙醇可抑制NMDA对培养皮层神经元的神经毒性。然而，已知NMDA拮抗剂和乙醇对某些神经元群有毒。在本研究中，我们研究了NMDA拮抗剂和乙醇是否在培养条件下诱导神经元凋亡。将大鼠皮质培养物（10天）暴露于MK801 （1 nM ~ 10 μM）和乙醇（50 ~ 300 mM）中24 ~ 48小时，可导致凋亡细胞呈剂量依赖性死亡。NMDA （25 μM和50 μM）可减弱mk801和乙醇诱导的细胞死亡。MK801和乙醇降低细胞内钙离子浓度。caspase-3的激活伴随着mk801和乙醇诱导的细胞死亡，并呈剂量依赖性。此外，环己亚胺（0.1和0.2 μg/ml）对MK801和乙醇诱导的细胞死亡和caspase-3活化具有保护作用。胰岛素样生长因子1 （5 ~ 20 ng/ml）对MK801和乙醇诱导的细胞死亡和caspase-3活化也有抑制作用。Ifenprodil是一种nr2b选择性NMDA拮抗剂，也可诱导凋亡细胞死亡和caspase-3活化。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细胞凋亡。

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.