Priestley T, Horne A L, McKernan R M, Kemp J A
Merck Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Harlow, U.K.
Brain Res. 1990 Oct 29;531(1-2):183-8. doi: 10.1016/0006-8993(90)90772-4.
The neuroprotective potential of an antagonist (7-chlorokynurenic acid (7-CIKYNA)) and a low efficacy partial agonist (HA-966) for the glycine modulatory site on the N-methyl-D-aspartate (NMDA) receptor complex has been examined using a neuronal cell culture/hypoxia model of neurodegeneration. Their effects were compared to those of the potent uncompetitive NMDA antagonist, MK-801. Hypoxic cell injury was assessed visually and quantified by measuring the appearance of two cytosolic enzymes, lactate dehydrogenase (LDH) and neurone specific enolase (NSE), in the culture medium. MK-801 prevented the hypoxia-induced cell mortality in a concentration-related manner with an IC50 of 15 nM against increases in LDH levels. HA-966 and 7-CIKYNA also produced concentration-related protective effects with IC50s of 175 and 18 microM, respectively. Although both glycine antagonists were considerably weaker than MK-801 their maximum neuroprotective effects were comparable to that produced by MK-801, i.e. complete protection. This indicates that the level of NMDA receptor activation which can take place in the presence of the partial agonist HA-966 is insufficient to cause permanent neuronal damage. Concentration-effect curves were similar when NSE was used as the marker enzyme, supporting previous observations that the increases in LDH levels accurately and specifically reflect neuronal cell death. These results provide further evidence that hypoxia-induced injury to cortical neuronal cultures is mediated by an excessive stimulation of NMDA receptors and that glycine-site antagonists and partial agonists may have therapeutic potential in conditions where pathologically high levels of NMDA receptor activation are thought to occur.
利用神经退行性变的神经元细胞培养/缺氧模型，研究了N-甲基-D-天冬氨酸（NMDA）受体复合物上甘氨酸调节位点的拮抗剂（7-氯犬尿氨酸（7-CIKYNA））和低效部分激动剂（HA-966）的神经保护潜力。将它们的作用与强效非竞争性NMDA拮抗剂MK-801的作用进行了比较。通过视觉评估缺氧细胞损伤，并通过测量培养基中两种胞质酶乳酸脱氢酶（LDH）和神经元特异性烯醇化酶（NSE）的出现进行定量。MK-801以浓度相关的方式预防了缺氧诱导的细胞死亡，对LDH水平升高的IC50为15 nM。HA-966和7-CIKYNA也产生了浓度相关的保护作用，IC50分别为175和18 μM。尽管两种甘氨酸拮抗剂都比MK-801弱得多，但其最大神经保护作用与MK-801产生的作用相当，即完全保护。这表明在部分激动剂HA-966存在下可能发生的NMDA受体激活水平不足以导致永久性神经元损伤。当使用NSE作为标记酶时，浓度-效应曲线相似，支持了先前的观察结果，即LDH水平的升高准确且特异性地反映了神经元细胞死亡。这些结果进一步证明，缺氧诱导的皮质神经元培养损伤是由NMDA受体的过度刺激介导的，并且甘氨酸位点拮抗剂和部分激动剂在认为发生病理性高水平NMDA受体激活的情况下可能具有治疗潜力。
