Postsynaptic Calcium Extrusion at the Mouse Neuromuscular Junction Alkalinizes the Synaptic Cleft.
Postsynaptic Calcium Extrusion at the Mouse Neuromuscular Junction Alkalinizes the Synaptic Cleft.
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DOI：
10.1523/jneurosci.0815-23.2023
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发表时间：
2023-08-09
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神经传递是由细胞外的pH值。碱化增强pH敏感的递质释放和受体激活，而酸化抑制这些过程，并可以激活酸敏感的电导在突触间隙。以往的研究表明，突触间隙可以酸化，因为突触囊泡释放和/或碱化，因为Ca 2+的质膜ATP酶（PMCA）的挤压。不同类型突触的变化方向不同。在哺乳动物神经肌肉接头（NMJ），在突触间隙中的pH瞬变的方向和幅度在传输过程中仍然是模糊的。我们着手阐明细胞外的pH值瞬变发生在这个胆碱能突触在接近生理条件下，并确定其来源。我们监测pH值依赖性的变化，在突触间隙的小鼠耳长提肌使用病毒表达的伪放射性探针pHusion-Ex的肌肉。使用来自两种性别的小鼠，当以50 Hz刺激连接的神经5 s时，发生显著且延长的碱化，这依赖于突触后细胞内Ca 2+释放。持续刺激较长的时间（20秒，50 Hz）造成额外的延长净酸化的裂缝。为了研究间隙碱性化的机制，我们使用肌肉表达的GCaMP 3来监测突触后Ca 2+的贡献。活动诱导的肌肉细胞内Ca 2+的释放与突触间隙的碱化呈正相关，而抑制PMCA显着降低间隙碱化的程度。因此，小鼠NMJ的胆碱能突触通常由于活动期间肌肉中释放的胞质Ca 2+而碱化，除非在高度剧烈的条件下，其中酸化占主导地位。突触间隙pH值的变化改变神经传递，作用于突触两侧的受体和通道。突触酸化与中枢和外周神经系统中的无数疾病有关。在这里，我们报告说，在近生理记录条件下的胆碱能神经肌肉接头显示使用依赖性的双向变化，突触间隙pH值立即碱化和长期刺激下的持久酸化。这些结果提供了进一步的洞察生理相关的变化，在胆碱能突触尚未被定义以前。了解和识别神经元活动期间和之后的突触pH瞬变提供了对短期突触可塑性突触的深入了解，并且可以识别疾病的治疗靶点。
Neurotransmission is shaped by extracellular pH. Alkalization enhances pH-sensitive transmitter release and receptor activation, whereas acidification inhibits these processes and can activate acid-sensitive conductances in the synaptic cleft. Previous work has shown that the synaptic cleft can either acidify because of synaptic vesicular release and/or alkalize because of Ca2+ extrusion by the plasma membrane ATPase (PMCA). The direction of change differs across synapse types. At the mammalian neuromuscular junction (NMJ), the direction and magnitude of pH transients in the synaptic cleft during transmission remain ambiguous. We set out to elucidate the extracellular pH transients that occur at this cholinergic synapse under near-physiological conditions and identify their sources. We monitored pH-dependent changes in the synaptic cleft of the mouse levator auris longus using viral expression of the pseudoratiometric probe pHusion-Ex in the muscle. Using mice from both sexes, a significant and prolonged alkalization occurred when stimulating the connected nerve for 5 s at 50 Hz, which was dependent on postsynaptic intracellular Ca2+ release. Sustained stimulation for a longer duration (20 s at 50 Hz) caused additional prolonged net acidification at the cleft. To investigate the mechanism underlying cleft alkalization, we used muscle-expressed GCaMP3 to monitor the contribution of postsynaptic Ca2+. Activity-induced liberation of intracellular Ca2+ in muscle positively correlated with alkalization of the synaptic cleft, whereas inhibiting PMCA significantly decreased the extent of cleft alkalization. Thus, cholinergic synapses of the mouse NMJ typically alkalize because of cytosolic Ca2+ liberated in muscle during activity, unless under highly strenuous conditions where acidification predominates. SIGNIFICANCE STATEMENT Changes in synaptic cleft pH alter neurotransmission, acting on receptors and channels on both sides of the synapse. Synaptic acidification has been associated with a myriad of diseases in the central and peripheral nervous system. Here, we report that in near-physiological recording conditions the cholinergic neuromuscular junction shows use-dependent bidirectional changes in synaptic cleft pH—immediate alkalinization and a long-lasting acidification under prolonged stimulation. These results provide further insight into physiologically relevant changes at cholinergic synapses that have not been defined previously. Understanding and identifying synaptic pH transients during and after neuronal activity provides insight into short-term synaptic plasticity synapses and may identify therapeutic targets for diseases.
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影响因子：
4.6
作者：
Blaustein M;Wirth S;Saldaña G;Piantanida AP;Bogetti ME;Martin ME;Colman-Lerner A;Uchitel OD
通讯作者：
Uchitel OD
影响因子：
5.3
作者：
Heredia DJ;Schubert D;Maligireddy S;Hennig GW;Gould TW
通讯作者：
Gould TW
影响因子：
3.3
作者：
Burette, A. C.;Strehler, E. E.;Weinberg, R. J.
通讯作者：
Weinberg, R. J.
藤壶肌肉细胞中耦合的Na外排和Ca涌入（Na/Ca交换）的动力学和化学计量。
影响因子：
3.8
作者：
RASGADOFLORES, H;SANTIAGO, EM;BLAUSTEIN, MP
通讯作者：
BLAUSTEIN, MP
DOI：
10.1152/ajpcell.00301.2013
发表时间：
2014-02-15
期刊：
American journal of physiology. Cell physiology
影响因子：
--
作者：
Urbano FJ;Lino NG;González-Inchauspe CM;González LE;Colettis N;Vattino LG;Wunsch AM;Wemmie JA;Uchitel OD
通讯作者：
Uchitel OD