Boikov Sergei I, Karelina Tatiana V, Sibarov Dmitry A, Antonov Sergei M
Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, Saint-Petersburg, Russia.
Front Pharmacol. 2024 Aug 2;15:1432718. doi: 10.3389/fphar.2024.1432718. eCollection 2024.
The open-channel block of -methyl-D-aspartate receptors (NMDARs) and their calcium-dependent desensitization (CDD) represent conventional mechanisms of glutamatergic synapse regulation. In neurotrauma, neurodegeneration, and neuropathic pain the clinical benefits of cure with memantine, ketamine, Mg, and some tricyclic antidepressants are often attributed to NMDAR open-channel block, while possible involvement of NMDAR CDD in the therapy is not well established. Here the effects of selective high-affinity sodium-calcium exchanger (NCX) isoform 1 inhibitor, SEA0400, on NMDA-activated whole-cell currents and their block by amitriptyline, desipramine and clomipramine recorded by patch-clamp technique in cortical neurons of primary culture were studied. We demonstrated that in the presence of extracellular Ca, 50 nM SEA0400 caused a reversible decrease of the steady-state amplitude of NMDAR currents, whereas loading neurons with BAPTA or the removal of extracellular Ca abolished the effect. The decrease did not exceed 30% of the amplitude and did not depend on membrane voltage. The external Mg block and 50 nM SEA0400 inhibition of currents were additive, suggesting their independent modes of action. In the presence of Ca SEA0400 speeded up the decay of NMDAR currents to the steady state determined by CDD. The measured IC value of 27 nM for SEA0400-induced inhibition coincides with that for NCX1. Presumably, SEA0400 effects are induced by an enhancement of NMDAR CDD through the inhibition of Ca extrusion by NCX1. SEA0400, in addition, at nanomolar concentrations could interfere with Ca-dependent effect of tricyclic antidepressants. In the presence of 50 nM SEA0400, the ICs for NMDAR inhibition by amitriptyline and desipramine increased by about 20 folds, as the Ca-dependent NMDAR inhibition disappeared. This observation highlights NCX1 involvement in amitriptyline and desipramine effects on NMDARs and unmasks competitive relationships between SEA0400 and these antidepressants. Neither amitriptyline nor desipramine could affect NCX3. The open-channel block of NMDARs by these substances was not affected by SEA0400. In agreement, SEA0400 did not change the IC for clomipramine, which acts as a pure NMDAR open-channel blocker. Thus, NCX seems to represent a promising molecular target to treat neurological disorders, because of the ability to modulate NMDARs by decreasing the open probability through the enhancement of their CDD.
N-甲基-D-天冬氨酸受体（NMDARs）的开放通道阻断及其钙依赖性脱敏（CDD）是谷氨酸能突触调节的传统机制。在神经创伤、神经退行性变和神经性疼痛中，美金刚、氯胺酮、镁和一些三环类抗抑郁药治疗的临床益处通常归因于NMDAR开放通道阻断，而NMDAR CDD在治疗中的可能作用尚未明确。本文研究了选择性高亲和力钠钙交换体（NCX）同工型1抑制剂SEA0400对原代培养皮层神经元中NMDA激活的全细胞电流及其被阿米替林、去甲替林和氯米帕明阻断的影响，采用膜片钳技术进行记录。我们证明，在细胞外钙存在的情况下，50 nM SEA0400导致NMDAR电流稳态幅度可逆性降低，而用BAPTA加载神经元或去除细胞外钙可消除该效应。降低幅度不超过电流幅度的30%，且不依赖于膜电压。细胞外镁阻断和50 nM SEA0400对电流的抑制作用具有加和性，表明它们的作用方式独立。在钙存在的情况下，SEA0400加速了NMDAR电流衰减至由CDD决定的稳态。测得SEA0400诱导抑制的IC值为27 nM，与NCX1的IC值一致。推测SEA0400的作用是通过抑制NCX1的钙外排增强NMDAR CDD而诱导的。此外，纳摩尔浓度的SEA0400可能会干扰三环类抗抑郁药的钙依赖性作用。在存在50 nM SEA0400的情况下，阿米替林和去甲替林对NMDAR抑制的IC50增加了约20倍，因为钙依赖性NMDAR抑制消失。这一观察结果突出了NCX1参与阿米替林和去甲替林对NMDARs的作用，并揭示了SEA0400与这些抗抑郁药之间的竞争关系。阿米替林和去甲替林均不影响NCX3。这些物质对NMDARs的开放通道阻断不受SEA0400影响。同样，SEA0400没有改变作为纯NMDAR开放通道阻断剂的氯米帕明的IC50。因此，由于NCX能够通过增强NMDAR的CDD降低其开放概率来调节NMDARs，它似乎是治疗神经系统疾病的一个有前景的分子靶点。
