Glutamate is traditionally viewed as the first messenger to activate NMDAR (N-methyl-d-aspartate receptor)-dependent cell death pathways in stroke^1,2, but unsuccessful clinical trials with NMDAR antagonists implicate the engagement of other mechanisms^3,4,5,6,7. Here we show that glutamate and its structural analogues, including NMDAR antagonist l-AP5 (also known as APV), robustly potentiate currents mediated by acid-sensing ion channels (ASICs) associated with acidosis-induced neurotoxicity in stroke⁴. Glutamate increases the affinity of ASICs for protons and their open probability, aggravating ischaemic neurotoxicity in both in vitro and in vivo models. Site-directed mutagenesis, structure-based modelling and functional assays reveal a bona fide glutamate-binding cavity in the extracellular domain of ASIC1a. Computational drug screening identified a small molecule, LK-2, that binds to this cavity and abolishes glutamate-dependent potentiation of ASIC currents but spares NMDARs. LK-2 reduces the infarct volume and improves sensorimotor recovery in a mouse model of ischaemic stroke, reminiscent of that seen in mice with Asic1a knockout or knockout of other cation channels^4,5,6,7. We conclude that glutamate functions as a positive allosteric modulator for ASICs to exacerbate neurotoxicity, and preferential targeting of the glutamate-binding site on ASICs over that on NMDARs may be strategized for developing stroke therapeutics lacking the psychotic side effects of NMDAR antagonists.

传统上，谷氨酸被视为在中风中激活 NMDAR（ N-甲基-d-天冬氨酸受体）依赖性细胞死亡途径的第一个信使^1,2 ，但 NMDAR 拮抗剂的不成功临床试验暗示其他机制的参与^{3,4,5 ,6,7} 。在这里，我们发现谷氨酸及其结构类似物，包括 NMDAR 拮抗剂l -AP5（也称为 APV），可以强烈增强酸敏感离子通道（ASIC）介导的电流，与酸中毒引起的中风神经毒性相关⁴ 。谷氨酸增加了 ASIC 对质子的亲和力及其开放概率，从而加剧了体外和体内模型中的缺血性神经毒性。定点诱变、基于结构的建模和功能测定揭示了 ASIC1a 胞外域中真正的谷氨酸结合腔。计算药物筛选发现了一种小分子 LK-2，它与该空腔结合并消除了 ASIC 电流的谷氨酸依赖性增强作用，但不影响 NMDAR。 LK-2 可减少缺血性中风小鼠模型中的梗塞体积并改善感觉运动恢复，这让人想起在Asic1a敲除或其他阳离子通道敲除的小鼠中观察到的情况^4,5,6,7 。我们得出的结论是，谷氨酸作为 ASIC 的正变构调节剂，会加剧神经毒性，并且优先靶向 ASIC 上的谷氨酸结合位点而不是 NMDAR 上的谷氨酸结合位点，可能有助于开发缺乏 NMDAR 拮抗剂精神病副作用的中风治疗方法。