Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, Federal Research Center "Kazan Scientific Center of RAS", 2/31 Lobachevsky Street, box 30, Kazan 420111, Russia; Institute of Neuroscience, Kazan State Medial University, 49 Butlerova Street, Kazan 420012, Russia.
Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, Federal Research Center "Kazan Scientific Center of RAS", 2/31 Lobachevsky Street, box 30, Kazan 420111, Russia.
Biochim Biophys Acta Mol Cell Biol Lipids. 2020 Sep;1865(9):158739. doi: 10.1016/j.bbalip.2020.158739. Epub 2020 May 16.
Olesoxime is a cholesterol-like neuroprotective compound that targets to mitochondrial voltage dependent anion channels (VDACs). VDACs were also found in the plasma membrane and highly expressed in the presynaptic compartment. Here, we studied the effects of olesoxime and VDAC inhibitors on neurotransmission in the mouse neuromuscular junction. Electrophysiological analysis revealed that olesoxime suppressed selectively evoked neurotransmitter release in response to a single stimulus and 20 Hz activity. Also olesoxime decreased the rate of FM1-43 dye loss (an indicator of synaptic vesicle exocytosis) at low frequency stimulation and 20 Hz. Furthermore, an increase in extracellular Cl enhanced the action of olesoxime on the exocytosis and olesoxime increased intracellular Cl levels. The effects of olesoxime on the evoked synaptic vesicle exocytosis and [Cl] were blocked by membrane-permeable and impermeable VDAC inhibitors. Immunofluorescent labeling pointed on the presence of VDACs on the synaptic membranes. Rotenone-induced mitochondrial dysfunction perturbed the exocytotic release of FM1-43 and cell-permeable VDAC inhibitor (but not olesoxime or impermeable VDAC inhibitor) partially mitigated the rotenone-driven alterations in the FM1-43 unloading and mitochondrial superoxide production. Thus, olesoxime restrains neurotransmission by acting on plasmalemmal VDACs whose activation can limit synaptic vesicle exocytosis probably via increasing anion flux into the nerve terminals.
奥昔莫司是一种类似胆固醇的神经保护化合物，作用于线粒体电压依赖性阴离子通道（VDACs）。VDACs 也存在于质膜中，在前突触区高表达。在此，我们研究了奥昔莫司和 VDAC 抑制剂对小鼠神经肌肉接头神经传递的影响。电生理分析显示，奥昔莫司选择性地抑制了对单个刺激和 20 Hz 活动的诱发神经递质释放。奥昔莫司还降低了低频刺激和 20 Hz 时 FM1-43 染料丢失的速率（突触囊泡胞吐作用的指示剂）。此外，细胞外 Cl-浓度的增加增强了奥昔莫司对胞吐作用的作用，奥昔莫司增加了细胞内 Cl-水平。奥昔莫司对诱发的突触囊泡胞吐作用和[Cl-]的作用被膜通透性和非通透性 VDAC 抑制剂阻断。免疫荧光标记指出 VDACs 存在于突触膜上。鱼藤酮诱导的线粒体功能障碍扰乱了 FM1-43 的胞吐释放，而细胞通透性 VDAC 抑制剂（而非奥昔莫司或非通透性 VDAC 抑制剂）部分减轻了 FM1-43 卸载和线粒体超氧产生的鱼藤酮驱动的改变。因此，奥昔莫司通过作用于质膜 VDACs 来抑制神经传递，其激活可能通过增加阴离子流入神经末梢来限制突触囊泡胞吐。
