Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria.
Institute of Physiology and Pathophysiology, University of Erlangen-Nürnberg, Erlangen, Germany.
Glia. 2023 Apr;71(4):945-956. doi: 10.1002/glia.24316. Epub 2022 Dec 10.
Signal propagation is the essential function of nerves. Lysophosphatidic acid 18:1 (LPA) allows the selective stimulation of calcium signaling in Schwann cells but not neurons. Here, the time course of slowing and amplitude reduction on compound action potentials due to LPA exposure was observed in myelinated and unmyelinated fibers of the mouse, indicating a clear change of axonal function. Teased nerve fiber imaging showed that Schwann cell activation is also present in axon-attached Schwann cells in freshly isolated peripheral rat nerves. The LPA receptor 1 was primarily localized at the cell extensions in isolated rat Schwann cells, suggesting a role in cell migration. Structural investigation of rat C-fibers demonstrated that LPA leads to an evagination of the axons from their Schwann cells. In A-fibers, the nodes of Ranvier appeared unchanged, but the Schmidt-Lanterman incisures were shortened and myelination reduced. The latter might increase leak current, reducing the potential spread to the next node of Ranvier and explain the changes in conduction velocity. The observed structural changes provide a plausible explanation for the functional changes in myelinated and unmyelinated axons of peripheral nerves and the reported sensory sensations such as itch and pain.
信号传递是神经的基本功能。溶血磷脂酸 18:1（LPA）允许 Schwann 细胞而非神经元选择性地刺激钙信号。在这里，观察到 LPA 暴露导致有髓和无髓纤维中复合动作电位的减速和幅度降低的时间过程，表明轴突功能发生明显变化。 teased 神经纤维成像显示，Schwann 细胞激活也存在于新鲜分离的大鼠周围神经中附着在轴突上的 Schwann 细胞中。LPA 受体 1 主要定位于分离的大鼠 Schwann 细胞的细胞延伸处，提示其在细胞迁移中发挥作用。对大鼠 C 纤维的结构研究表明，LPA 导致轴突从 Schwann 细胞向外突出。在 A 纤维中，Ranvier 结没有变化，但 Schmidt-Lanterman 切迹缩短，髓鞘减少。后者可能会增加漏电流，从而减少向Ranvier 下一个结的电位传播，并解释传导速度的变化。观察到的结构变化为周围神经有髓和无髓轴突的功能变化以及报告的感觉（如瘙痒和疼痛）提供了合理的解释。
