Similar electrophysiological changes in axotomized and neighboring intact dorsal root ganglion neurons
Similar electrophysiological changes in axotomized and neighboring intact dorsal root ganglion neurons
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DOI：
10.1152/jn.00855.2002
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发表时间：
2003-03-01
影响因子：
2.5
通讯作者：
LaMotte, RH
中科院分区：
文献类型：
--
作者：
Ma, C;Shu, YS;LaMotte, RH
我们研究了电生理变化，慢性轴突切断和邻近完整的背根神经节（DRG）神经元在大鼠后，无论是外周轴突切断术的L5脊神经结扎（SNL）或中央轴突切断术产生的L5部分根切断术（PR）。SNL产生持久的痛觉过敏，点状压痕和触觉异常性疼痛，无害的同侧脚的伤害。PR产生同侧痛觉过敏，无异常性疼痛，第10天恢复。细胞内记录在体内从轴突切断和完整的DRG神经元的细胞体（胞体）获得，其中一些具有功能鉴定的外周感受野。PR只产生轻微的电生理变化，轴突切断和完整的体在L5 DRG。与此相反，广泛的变化，观察SNL后，在大型和中型，但不是小型，完整的（L4）以及轴突切断（L5）DRG神经元的胞体。这些变化包括（相对于假手术值）较高的输入电阻、较低的电流和电压阈值以及持续时间较长和上升和下降速率较慢的动作电位。自发活动的发生率，记录在体外背根纤维的细胞外，SNL后显着较高（相对于假手术），但不是PR后，发生在有髓纤维，但不是无髓纤维从L4（9.1%）和L5（16.7%）DRG。我们假设SNL后轴突切断和完整背根神经节神经元的电生理特性变化是由与沃勒变性相关的机制产生的，并且完整神经元的过度兴奋可能导致SNL诱导的痛觉过敏和异常性疼痛。
We investigated electrophysiological changes in chronically axotomized and neighboring intact dorsal root ganglion (DRG) neurons in rats after either a peripheral axotomy consisting of an L5 spinal nerve ligation (SNL) or a central axotomy produced by an L5 partial rhizotomy (PR). SNL produced lasting hyperalgesia to punctate indentation and tactile allodynia to innocuous stroking of the foot ipsilateral to the injury. PR produced ipsilateral hyperalgesia without allodynia with recovery by day 10. Intracellular recordings were obtained in vivo from the cell bodies (somata) of axotomized and intact DRG neurons, some with functionally identified peripheral receptive fields. PR produced only minor electrophysiological changes in both axotomized and intact somata in L5 DRG. In contrast, extensive changes were observed after SNL in large- and medium-sized, but not small-sized, somata of intact (L4) as well as axotomized (L5) DRG neurons. These changes included (in relation to sham values) higher input resistance, lower current and voltage thresholds, and action potentials with longer durations and slower rising and falling rates. The incidence of spontaneous activity, recorded extracellularly from dorsal root fibers in vitro, was significantly higher (in relation to sham) after SNL but not after PR, and occurred in myelinated but not unmyelinated fibers from both L4 (9.1%) and L5 (16.7%) DRGs. We hypothesize that the changes in the electrophysiological properties of axotomized and intact DRG neurons after SNL are produced by a mechanism associated with Wallerian degeneration and that the hyperexcitability of intact neurons may contribute to SNL-induced hyperalgesia and allodynia.