Brain-derived neurotrophic factor/neurotrophin 3 regulate axon initial segment location and affect neuronal excitability in cultured hippocampal neurons
Brain-derived neurotrophic factor/neurotrophin 3 regulate axon initial segment location and affect neuronal excitability in cultured hippocampal neurons
复制标题
脑源性神经营养因子/神经营养蛋白 3 调节轴突起始段位置并影响培养海马神经元的神经元兴奋性
DOI：
10.1111/jnc.14050
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发表时间：
2017-07-01
影响因子：
4.7
通讯作者：
Chai, Zhen
中科院分区：
文献类型：
--
作者：
Guo, Yu;Su, Zi-jun;Chai, Zhen
轴突起始段(AIS)的可塑性调节动作电位的起始和神经元的兴奋性，近年来引起了人们的极大兴趣。AIS的可塑性表现为离子通道的调制或AIS结构的变化。然而，AIS的结构可塑性的潜在机制还不是很清楚。在这里，我们结合免疫荧光、膜片钳记录和药理学方法，在培养的海马神经元中研究在发育过程中参与AIS结构可塑性的因素。随着神经元密度的降低，AIS到胞体的距离增加，神经元的兴奋性降低，表现为动作电位阈值和放电电流阈值的增加。AIS的这种位置变化与细胞分泌物质有关，包括脑源性神经营养因子(BDNF)和神经营养素3(NT3)。事实上，用TrkB-FC阻断BDNF和NT3消除了从高密度培养中收集的条件培养液对AIS重新定位的影响。升高BDNF或NT3的胞外浓度可促进AIS向胞体近端的移动，并增强神经元的兴奋性。此外，神经营养因子受体TrkB和TrkC的敲除导致了AIS的远端移动。我们的结果表明，BDNF和NT3调节AIS的定位和神经元的兴奋性。神经营养因子的这些调节功能提供了对AIS生物学基础的分子机制的洞察。
Plasticity of the axon initial segment (AIS) has aroused great interest in recent years because it regulates action potential initiation and neuronal excitability. AIS plasticity manifests as modulation of ion channels or variation in AIS structure. However, the mechanisms underlying structural plasticity of the AIS are not well understood. Here, we combined immunofluorescence, patch-clamp recordings, and pharmacological methods in cultured hippocampal neurons to investigate the factors participating in AIS structural plasticity during development. With lowered neuronal density, the distance between the AIS and the soma increased, while neuronal excitability decreased, as shown by the increased action potential threshold and current threshold for firing an action potential. This variation in the location of the AIS was associated with cellular secretory substances, including brain-derived neurotrophic factor (BDNF) and neurotrophin 3 (NT3). Indeed, blocking BDNF and NT3 with TrkB-Fc eliminated the effect of conditioned medium collected from high-density cultures on AIS relocation. Elevating the extracellular concentration of BDNF or NT3 promoted movement of the AIS proximally to the soma and increased neuronal excitability. Furthermore, knockdown of neurotrophin receptors TrkB and TrkC caused distal movement of the AIS. Our results demonstrate that BDNF and NT3 regulate AIS location and neuronal excitability. These regulatory functions of neurotrophic factors provide insight into the molecular mechanisms underlying AIS biology.