研究人员发现，在啮齿动物中，神经元活动提高了位于有髓鞘轴突初始段（AIS）和Ranvier结的动作电位产生点附近的星形胶质细胞过程的细胞内钙浓度（[Ca2+]i）。这释放了三磷酸腺苷，它在细胞外转化为腺苷，从而通过A2a受体激活了含有HCN2的阳离子通道，这些通道调节了有髓轴突功能的两个方面：AIS的兴奋性和动作电位传播的速度。因此，在清醒和睡眠状态之间或在能量匮乏期间，星形胶质细胞衍生的腺苷水平变化可以控制白质信息流和神经回路功能。
据介绍，在大脑灰质中，星形胶质细胞调节突触特性，但它们在白质中的作用还不清楚，在白质中，有髓鞘的轴突在灰质区域之间迅速传递信息。
附：英文原文
Title: Astrocyte Ca2+-evoked ATP release regulates myelinated axon excitability and conduction speed
Author: Jonathan Lezmy, I. Lorena Arancibia-Cárcamo, Tania Quintela-López, Diane L. Sherman, Peter J. Brophy, David Attwell
Issue&Volume: 2021-10-15
Abstract: In the brain’s gray matter, astrocytes regulate synapse properties, but their role is unclear for the white matter, where myelinated axons rapidly transmit information between gray matter areas. We found that in rodents, neuronal activity raised the intracellular calcium concentration ([Ca2+]i) in astrocyte processes located near action potential–generating sites in the axon initial segment (AIS) and nodes of Ranvier of myelinated axons. This released adenosine triphosphate, which was converted extracellularly to adenosine and thus, through A2a receptors, activated HCN2-containing cation channels that regulate two aspects of myelinated axon function: excitability of the AIS and speed of action potential propagation. Variations in astrocyte-derived adenosine level between wake and sleep states or during energy deprivation could thus control white matter information flow and neural circuit function.
DOI: abh2858
Source: https://www.science.org/doi/10.1126/science.abh2858