UNIS, INSERM UMR_S 1072, Aix-Marseille Université, 13015, Marseille, France.
Instituto Cajal, CSIC, Madrid, 28002, Spain.
Sci Rep. 2017 Mar 22;7(1):315. doi: 10.1038/s41598-017-00388-1.
Axonal ion channels control spike initiation and propagation along the axon and determine action potential waveform. We show here that functional suppression of axonal Kv1 channels with local puff of dendrotoxin (DTx), laser or mechanical axotomy significantly increased excitability measured in the cell body. Importantly, the functional effect of DTx puffing or axotomy was not limited to the axon initial segment but was also seen on axon collaterals. In contrast, no effects were observed when DTx was puffed on single apical dendrites or after single dendrotomy. A simple model with Kv1 located in the axon reproduced the experimental observations and showed that the distance at which the effects of axon collateral cuts are seen depends on the axon space constant. In conclusion, Kv1 channels located in the axon proper greatly participate in intrinsic excitability of CA3 pyramidal neurons. This finding stresses the importance of the axonal compartment in the regulation of intrinsic neuronal excitability.
轴突离子通道控制着轴突上的尖峰起始和传播，并决定动作电位的波形。我们在这里表明，用局部喷射树突毒素（DTx）、激光或机械轴突切断来抑制轴突 Kv1 通道，可显著增加在细胞体中测量到的兴奋性。重要的是，DTx 喷射或轴突切断的功能效应不仅局限于轴突起始段，也可见于轴突侧支。相比之下，当 DTx 喷射到单个顶树突或单个树突切断后，没有观察到效果。一个简单的模型表明，Kv1 位于轴突中，可重现实验观察结果，并表明可以看到轴突侧支切割效果的距离取决于轴突空间常数。总之，位于轴突中的 Kv1 通道极大地参与了 CA3 锥体神经元的固有兴奋性。这一发现强调了轴突区在调节内在神经元兴奋性中的重要性。
