Planells-Cases Rosa, Montoliu Carmina, Humet Marc, Fernández Asia M, García-Martínez Carolina, Valera Elvira, Merino Jaime M, Pérez-Payá Enrique, Messeguer Angel, Felipo Vicente, Ferrer-Montiel Antonio
Centro de Biología Molecular y Celular, Universidad Miguel Hernández, Ed. Torregaitán, Avenida Ferrocaril s/n, 03202 Elche, Alicante, Spain.
J Pharmacol Exp Ther. 2002 Jul;302(1):163-73. doi: 10.1124/jpet.302.1.163.
Excitotoxicity has been implicated in the etiology of ischemic stroke, chronic neurodegenerative disorders, and very recently, in glioma growth. Thus, the development of novel neuroprotectant molecules that reduce excitotoxic brain damage is vigorously pursued. We have used an ionic current block-based cellular assay to screen a synthetic combinatorial library of trimers of N-alkylglycines on the N-methyl-D-aspartate (NMDA) receptor, a well known molecular target involved in excitotoxicity. We report the identification of a family of N-alkylglycines that selectively blocked the NMDA receptor. Notably, compound 3,3-diphenylpropyl-N-glycinamide (referred to as N20C) inhibited NMDA receptor channel activity with micromolar affinity, fast on-off blockade kinetics, and strong voltage dependence. Molecule N20C did not act as a competitive glutamate or glycine antagonist. In contrast, saturation of the blocker binding site with N20C prevented dizolcipine (MK-801) blockade of the NMDA receptor, implying that both drugs bind to the same receptor site. The N-alkylglycine efficiently prevented in vitro excitotoxic neurodegeneration of cerebellar and hippocampal neurons in culture. Attenuation of neuronal glutamate/NMDA-induced Ca(2+) overload and subsequent modulation of the glutamate-nitric oxide-cGMP pathway seems to underlie N20C neuroprotection. Noteworthy, this molecule exhibited significant in vivo neuroprotectant activity against an acute, severe, excitotoxic insult. Taken together, these findings indicate that N-alkylglycine N20C is a novel, low molecular weight, moderate-affinity NMDA receptor open channel blocker with in vitro and in vivo neuroprotective activity, which, in due turn, may become a tolerated drug for the treatment of neurodegenerative diseases and cancer.
兴奋性毒性已被认为与缺血性中风、慢性神经退行性疾病的病因有关，最近还与胶质瘤生长有关。因此，人们大力寻求开发能减少兴奋性毒性脑损伤的新型神经保护分子。我们利用基于离子电流阻断的细胞试验，在N-甲基-D-天冬氨酸（NMDA）受体上筛选N-烷基甘氨酸三聚体的合成组合文库，NMDA受体是参与兴奋性毒性的一个众所周知的分子靶点。我们报告了一类选择性阻断NMDA受体的N-烷基甘氨酸的鉴定。值得注意的是，化合物3,3-二苯基丙基-N-甘氨酰胺（称为N20C）以微摩尔亲和力、快速的开-关阻断动力学和强电压依赖性抑制NMDA受体通道活性。分子N20C不作为竞争性谷氨酸或甘氨酸拮抗剂。相反，用N20C使阻断剂结合位点饱和可防止地卓西平（MK-801）对NMDA受体的阻断，这意味着两种药物都结合到同一受体位点。N-烷基甘氨酸有效地预防了培养中小脑和海马神经元的体外兴奋性毒性神经变性。神经元谷氨酸/NMDA诱导的Ca(2+)超载的减轻以及随后对谷氨酸-一氧化氮-cGMP途径的调节似乎是N20C神经保护作用的基础。值得注意的是，该分子对急性、严重的兴奋性毒性损伤表现出显著的体内神经保护活性。综上所述，这些发现表明N-烷基甘氨酸N20C是一种新型的、低分子量、中等亲和力的NMDA受体开放通道阻断剂，具有体外和体内神经保护活性，进而可能成为治疗神经退行性疾病和癌症的耐受性药物。
