Perampanel (PMP) is a third-generation antiseizure drug reported to be a potent and selective noncompetitive negative allosteric modulator of one subfamily of ionotropic glutamate receptor (iGluR), the α-amino-3-hydroxy-S-methylisoxazole-4-propionic acid receptors (AMPARs). However, the recent structural resolution of AMPARs in complex with PMP revealed that its binding pocket is formed from residues that are largely conserved in two members of another family of iGluRs, the GluK4 and GluK5 kainate receptor (KAR) subunits. We show here that PMP inhibits both recombinant and neuronal KARs, contrary to the previous reports, and that the negative allosteric modulator (NAM) activity requires GluK5 subunits to be channel constituents. PMP inhibited heteromeric GluK1/GluK5 and GluK2/GluK5 KARs at IC₅₀ values comparable to that for AMPA receptors but was much less potent on homomeric GluK1 or GluK2 KARs. The auxiliary subunits Neto1 or Neto2 also made GluK2-containing KARs more sensitive to inhibition. Finally, PMP inhibited mouse neuronal KARs containing GluK5 subunits and Neto proteins in nociceptive dorsal root ganglia neurons and hippocampal mossy fiber–CA3 pyramidal neuron synapses. These data suggest that clinical actions of PMP could arise from differential inhibition of AMPAR or KAR signaling and that more selective drugs might maintain antiseizure efficacy while reducing adverse effects.

SIGNIFICANCE STATEMENT PMP is a regulatory approved antiseizure drug used for refractory partial-onset and generalized tonic-clonic seizures that acts as a selective negative allosteric modulator of AMPARs. Here, we demonstrate that PMP inhibits KARs, a second family of ionotropic glutamate receptors, in addition to AMPARs. NAM activity on KARs required GluK5 subunits or Neto auxiliary subunits as channel constituents. KAR inhibition, therefore, could contribute to PMP antiseizure action or the adverse effects that are significant with this drug. Drug discovery aimed at more selective allosteric modulators that discriminate between AMPARs and KARs could yield next-generation drugs with improved therapeutic profiles for treatment of epilepsy.

吡仑帕奈 (PMP) 是一种第三代抗癫痫药物，据报道是离子型谷氨酸受体 (iGluR) 一个亚家族（α-氨基-3-羟基-S-甲基异恶唑-4-丙酸）的有效、选择性非竞争性负变构调节剂受体（AMPAR）。然而，最近 AMPAR 与 PMP 复合物的结构解析表明，其结合口袋是由在另一个 iGluR 家族的两个成员（GluK4 和 GluK5 红藻氨酸受体 (KAR) 亚基）中很大程度上保守的残基形成的。我们在这里表明，与之前的报道相反，PMP 抑制重组 KAR 和神经元 KAR，并且负变构调节剂 (NAM) 活性需要 GluK5 亚基作为通道成分。 PMP 抑制异聚 GluK1/GluK5 和 GluK2/GluK5 KAR 的 IC ₅₀值与 AMPA 受体相当，但对同聚 GluK1 或 GluK2 KAR 的效力要低得多。辅助亚基 Neto1 或 Neto2 也使含有 GluK2 的 KAR 对抑制更加敏感。最后，PMP 抑制小鼠伤害性背根神经节神经元和海马苔藓纤维 - CA3 锥体神经元突触中含有 GluK5 亚基和 Neto 蛋白的神经元 KAR。这些数据表明，PMP 的临床作用可能源于 AMPAR 或 KAR 信号传导的差异抑制，并且更具选择性的药物可能会保持抗癫痫疗效，同时减少不良反应。

意义声明PMP 是一种经监管部门批准的抗癫痫药物，用于治疗难治性部分发作和全身强直阵挛性癫痫发作，可作为 AMPAR 的选择性负变构调节剂。在这里，我们证明 PMP 抑制 KAR，这是除 AMPAR 之外的第二个离子型谷氨酸受体家族。 KAR 上的 NAM 活性需要 GluK5 亚基或 Neto 辅助亚基作为通道成分。因此，KAR 抑制可能有助于 PMP 抗癫痫作用或该药物的显着副作用。针对区分 AMPAR 和 KAR 的更具选择性变构调节剂的药物发现可能会产生具有改善的癫痫治疗效果的下一代药物。