Frequency-dependent Modulation of Synaptic Transmission and Plasticity by pH

脑细胞内pH（pHi）和细胞外pH（pHo）的调节对于优化神经元的功能至关重要。 兴奋性钠偶联二氢叶酸转运蛋白（NCBTs）-特别是星形胶质细胞的产电 Na/碳酸氢盐协同转运蛋白NBCe 1将pH变化与神经元活动结合起来，是神经元活动的关键调节因子。 尽管pH调节和NBCe 1在大脑中的丰度具有明显的重要性，但 NBCe 1和相关的pH值变化在调节突触传递和突触可塑性中的作用还没有被证实。 鉴定目前的目标是使用分子和药理学工具与电生理 脑切片研究中的方法来研究NBCe 1和相关的pH变化在调节脑缺血中的作用。 海马突触功能目的1是解决NBCe 1抑制基础、低频 突触传递急性海马CA 1区细胞外和全细胞联合记录 来自野生型和NBCe 1敲除（KO）小鼠的切片将用于研究NBCe 1在调节细胞凋亡中的作用。 海马CA 1区对低频（0.1 Hz）细胞外刺激反应的突触传递和峰化 刺激. NBCe 1抑制剂（S 0859和功能阻断L3抗体）的作用， 刺激L4抗体，以及NBCe 1 KO小鼠中NBCe 1向星形胶质细胞的病毒恢复。 pH敏感的微电极和染料将被用来检查相关的变化，在pH值，以及pH值的 星形胶质细胞和突触前末梢来检验抑制NBCe 1刺激基底突触的假说。 通过增强细胞外碱性转移来传递（建立的常规模型）。目标2是解决 NBCe 1增强高频突触传递和长时程可塑性的假说。的 针对目标1描述的分子和药理学工具和方法将用于检查兴奋性 突触反应，但对高频（50 Hz）细胞外刺激的反应。pH测量将 在细胞外间隙、星形胶质细胞和突触前神经末梢中进行，以检验以下假设： NBCe 1刺激高频突触传递和长时程增强（LTP）涉及 抑制活动诱发的突触前pHi降低（新机制）。基础机制，如 对于这两个目的，将评估突触前和突触后反应以及特异性受体的作用。结果将 揭示NBCe 1是调节突触传递的生理学上重要的酸碱转运蛋白 和LTP通过pH的变化，这取决于频率刺激。结果将有助于我们 了解NBCe 1和相关的pH值变化在神经元活动，癫痫发作，缺血和缺氧。

The regulation of intracellular pH (pHi) and extracellular pH (pHo) of brain is critical for optimizing neuronal excitability. Na-Coupled Bicarbonate Transporters (NCBTs) —particularly the astrocytic electrogenic Na/bicarbonate cotransporter NBCe1 that couples changes in pH with neuronal activity— are key regulators of brain pH. Despite the clear importance of pH regulation and the abundance of NBCe1 in brain, the role of NBCe1 and associated pH changes in modulating synaptic transmission and synaptic plasticity has not be identified. The current objective is to use molecular and pharmacological tools with electrophysiological approaches in brain-slice studies to investigate the role of NBCe1 and associated pH changes in modulating hippocampal synaptic function. Aim 1 is to address the hypothesis that NBCe1 dampens basal, low-frequency synaptic transmission. A combination of extracellular and whole-cell recordings in CA1 of acute hippocampal slices from wild-type and NBCe1 knockout (KO) mice will be used to investigate the role of NBCe1 in regulating synaptic transmission and spiking in hippocampal CA1 in response to low-frequency (0.1 Hz) extracellular stimulation. The effects of NBCe1 inhibitors (S0859 and a function blocking L3 antibody), a function stimulating L4 antibody, and viral restoration of NBCe1 into astrocytes in NBCe1 KO mice will be determined. pH-sensitive microelectrodes and dyes will be used to examine associated changes in pHo, as well as the pH of astrocytes and presynaptic terminals to test the hypothesis that inhibiting NBCe1 stimulates basal synaptic transmission by enhancing the extracellular alkaline shift (established conventional model). Aim 2 is to address the hypothesis that NBCe1 enhances high-frequency synaptic transmission and long-term plasticity. The molecular and pharmacological tools and approaches described for Aim 1 will be used to examine excitatory synaptic responses, but in response to high-frequency (50 Hz) extracellular stimulation. pH measurements will be made in the extracellular space, astrocytes, and presynaptic nerve terminals to test the hypothesis that NBCe1 stimulation of high-frequency synaptic transmission and long-term potentiation (LTP) involves dampening of the activity-evoked presynaptic pHi decrease (new mechanism). Underlying mechanisms such as pre- vs postsynaptic responses and the role of specific receptors will be evaluated for both Aims. Results will reveal that NBCe1 is a physiologically important acid-base transporter that modulates synaptic transmission and LTP through changes in pH that are dependent on frequency stimulation. The results will contribute to our understanding of NBCe1 and associated pH changes in neuronal activity, seizures, ischemia, and hypoxia.