Unmyelinated visceral afferents exhibit frequency dependent action potential broadening while myelinated visceral afferents do not
Unmyelinated visceral afferents exhibit frequency dependent action potential broadening while myelinated visceral afferents do not
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DOI：
10.1016/j.neulet.2007.05.036
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发表时间：
2007-06-21
影响因子：
2.5
通讯作者：
Schild, John H.
中科院分区：
文献类型：
--
作者：
Li, Bai-Yan;Feng, Bin;Schild, John H.
内脏器官系统产生的感觉信息被编码成动作电位序列，沿着传入纤维传播到中枢神经系统中的目标核。这些信息流的范围从与感觉转导事件良好同步的动作电位的严格模式到与感觉输入没有明确相关性的不规则、无模式的放电。一般来说，这些传入通路可分为无髓纤维和有髓纤维类型。我们的实验室对这两种类型的传入神经之间的功能差异有着长期的兴趣，这些差异涉及将感觉信息预处理为动作电位序列（同步性、频率、持续时间等）、这种感觉输入对中枢神经系统的反射作用以及产生这些独特细胞类型的电生理特性的离子通道。本研究的目的是确定无髓鞘和有髓迷走神经传入的躯体动作电位特征对不同速率的感觉神经刺激的反应是否存在功能差异。我们的结果表明，体细胞动作电位的活动和频率依赖性增宽在无髓鞘迷走神经传入中非常显着，但在有髓鞘迷走神经传入中则不然。尖峰加宽通常会导致 Ca2+ 离子流入增加，这与细胞体和中枢突触末端的多种调节机制（例如神经递质释放增加）有关。我们的结论是，我们的观察结果表明，无髓鞘和有髓迷走神经传入产生的感觉信息的神经整合机制存在根本不同的机制。 (c) 2007 Elsevier Ireland Ltd. 保留所有权利。
Sensory information arising from visceral organ systems is encoded into action potential trains that propagate along afferent fibers to target nuclei in the central nervous system. These information streams range from tight patterns of action potentials that are well synchronized with the sensory transduction event to irregular, patternless discharge with no clear correlation to the sensory input. In general terms these afferent pathways can be divided into unmyelinated and myelinated fiber types. Our laboratory has a long standing interest in the functional differences between these two types of afferents in terms of the preprocessing of sensory information into action potential trains (synchrony, frequency, duration, etc.), the reflexogenic consequences of this sensory input to the central nervous system and the ionic channels that give rise to the electrophysiological properties of these unique cell types. The aim of this study was to determine whether there were any functional differences in the somatic action potential characteristics of unmyelinated and myelinated vagal afferents in response to different rates of sensory nerve stimulation. Our results showed that activity and frequency-dependent widening of the somatic action potential was quite prominent in unmyelinated but not myelinated vagal afferents. Spike broadening often leads to increased influx of Ca2+ ions that has been associated with a diverse range of modulatory mechanisms both at the cell body and central synaptic terminations (e.g. increased neurotransmitter release.) We conclude that our observations are indicative of fundamentally different mechanisms for neural integration of sensory information arising from unmyelinated and myelinated vagal afferents. (c) 2007 Elsevier Ireland Ltd. All rights reserved.