Tai K K, Blondelle S E, Ostresh J M, Houghten R A, Montal M
Section of Neurobiology, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0366, USA.
Proc Natl Acad Sci U S A. 2001 Mar 13;98(6):3519-24. doi: 10.1073/pnas.061449498.
Excitotoxicity, resulting from sustained activation of glutamate receptors of the N-methyl-d-aspartate (NMDA) subtype, is considered to play a causative role in the etiology of ischemic stroke and several neurodegenerative diseases. The NMDA receptor is therefore a target for the development of neuroprotective agents. Here, we identify an N-benzylated triamine (denoted as NBTA) as a highly selective and potent NMDA-receptor channel blocker selected by screening a reduced dipeptidomimetic synthetic combinatorial library. NBTA blocks recombinant NMDA receptors expressed in Xenopus laevis oocytes with a mean IC(50) of 80 nM; in contrast, it does not block GluR1, a glutamate receptor of the non-NMDA subtype. The blocking activity of NBTA on NMDA receptors exhibits the characteristics of an open-channel blocker: (i) no competition with agonists, (ii) voltage dependence, and (iii) use dependence. Significantly, NBTA protects rodent hippocampal neurons from NMDA receptor, but not kainate receptor-mediated excitotoxic cell death, in agreement with its selective action on the corresponding recombinant receptors. Mutagenesis data indicate that the N site, a key asparagine on the M2 transmembrane segment of the NR1 subunit, is the main determinant of the blocker action. The results highlight the potential of this compound as a neuroprotectant.
由N-甲基-D-天冬氨酸（NMDA）亚型谷氨酸受体的持续激活所导致的兴奋毒性，被认为在缺血性中风和几种神经退行性疾病的病因学中起致病作用。因此，NMDA受体是神经保护剂开发的一个靶点。在此，我们鉴定出一种N-苄基化三胺（记为NBTA），它是通过筛选一个简化的二肽模拟合成组合文库而选出的一种高选择性且强效的NMDA受体通道阻滞剂。NBTA阻断非洲爪蟾卵母细胞中表达的重组NMDA受体，平均半数抑制浓度（IC50）为80 nM；相比之下，它不阻断非NMDA亚型的谷氨酸受体GluR1。NBTA对NMDA受体的阻断活性表现出开放通道阻滞剂的特征：（i）不与激动剂竞争；（ii）电压依赖性；（iii）使用依赖性。重要的是，NBTA保护啮齿动物海马神经元免受NMDA受体介导的兴奋毒性细胞死亡，但不能保护其免受海人藻酸受体介导的兴奋毒性细胞死亡，这与其对相应重组受体的选择性作用一致。诱变数据表明，N位点是NR1亚基M2跨膜片段上的一个关键天冬酰胺，是该阻滞剂作用的主要决定因素。这些结果突出了该化合物作为神经保护剂的潜力。
