加拿大阿尔伯塔大学David J. Bennett团队近期取得重要工作进展，他们研究发现GABA通过脊髓中感觉轴突的分支点促进尖峰传播。相关研究成果2022年9月26日在线发表于《自然—神经科学》杂志上。

研究人员直接用光遗传学或通过皮肤刺激间接激活GAD2⁺神经元，实际上促进了对啮齿动物和人类运动神经元的感觉反馈。位于感觉轴突Ranvier节点处或附近的GABA_A受体，通过防止在许多轴突分支点处的尖峰传播失败而导致这种促进作用，否则这种情况在没有GABA的情况下很常见。相比之下，轴突末端通常缺乏GABA_A受体，因此不能抑制递质释放到运动神经元上，这与引起突触前抑制的GABA_B受体不同。节点和分支点附近的GABA能神经支配允许各个分支自主发挥作用，GAD2⁺神经元调节哪些分支传导，为神经元网络添加一个计算层，产生运动并可能推广到其他中枢神经系统轴突。

据介绍，运动和姿势依赖于特殊的GABA能神经元（GAD2⁺）调节的感觉反馈，GABA能神经元在有髓神经的本体感觉轴突上形成轴突接触，并被认为是抑制性的。

附：英文原文

Title: GABA facilitates spike propagation through branch points of sensory axons in the spinal cord

Author: Hari, Krishnapriya, Lucas-Osma, Ana M., Metz, Krista, Lin, Shihao, Pardell, Noah, Roszko, David A., Black, Sophie, Minarik, Anna, Singla, Rahul, Stephens, Marilee J., Pearce, Robert A., Fouad, Karim, Jones, Kelvin E., Gorassini, Monica A., Fenrich, Keith K., Li, Yaqing, Bennett, David J.

Issue&Volume: 2022-09-26

Abstract: Movement and posture depend on sensory feedback that is regulated by specialized GABAergic neurons (GAD2+) that form axo-axonic contacts onto myelinated proprioceptive sensory axons and are thought to be inhibitory. However, we report here that activating GAD2+ neurons directly with optogenetics or indirectly by cutaneous stimulation actually facilitates sensory feedback to motor neurons in rodents and humans. GABAA receptors located at or near nodes of Ranvier of sensory axons cause this facilitation by preventing spike propagation failure at the many axon branch points, which is otherwise common without GABA. In contrast, GABAA receptors are generally lacking from axon terminals and so cannot inhibit transmitter release onto motor neurons, unlike GABAB receptors that cause presynaptic inhibition. GABAergic innervation near nodes and branch points allows individual branches to function autonomously, with GAD2+ neurons regulating which branches conduct, adding a computational layer to the neuronal networks generating movement and likely generalizing to other central nervous system axons.

DOI: 10.1038/s41593-022-01162-x

Source: https://www.nature.com/articles/s41593-022-01162-x