Fields R D, Neale E A, Nelson P G
Laboratory of Developmental Neurobiology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892.
J Neurosci. 1990 Sep;10(9):2950-64. doi: 10.1523/JNEUROSCI.10-09-02950.1990.
A noninvasive method of electric stimulation was used in cell culture preparations to determine the effects of patterned electrical activity on the morphology and motility of mammalian central nervous system growth cones. Neurites from dorsal root ganglion (DRG) neurons of fetal mice were allowed to grow under the barrier of an insert placed in culture dishes. The insert confined the cell bodies within separate experimental and control compartments, and provided a means of exciting action potentials in the growing neurites by extracellular current pulses delivered across the barrier. A phasic pattern of stimulation caused immediate retraction of the filopodia and lamellipodium. Further outgrowth was halted and in many cases retraction of the neurite ensued. No changes in morphology or growth cone motility were evoked by electric stimulation when action potentials were blocked with 1 microM tetrodotoxin (TTX). These effects depended on the rate, pattern, and duration of stimulation. Phasic stimulation was more effective than stimulation with the same number of impulses delivered at a constant frequency. An important new observation was that cultures exposed to phasic stimulation for several hours contained actively growing neurites with normal growth cones which were insensitive to the stimulus. This apparent accommodation in neurites exposed to chronic stimulation may involve processes that regulate calcium conductance or buffering. Cessation of neurite outgrowth by action potentials could represent one mechanism linking morphological and functional characteristics in the developing CNS of mammals, by stabilizing the outgrowth of neurites forming appropriate synaptic contacts and leading to the retraction of growth cones from collaterals that have not formed appropriate contacts at the time the neuron enters into a functionally active circuit.
在细胞培养制剂中使用了一种非侵入性电刺激方法，以确定模式化电活动对哺乳动物中枢神经系统生长锥的形态和运动性的影响。将来自胎鼠背根神经节（DRG）神经元的神经突置于培养皿中的插入物屏障下生长。该插入物将细胞体限制在单独的实验和对照隔室内，并提供了一种通过跨屏障传递的细胞外电流脉冲在生长的神经突中激发动作电位的方法。阶段性刺激模式导致丝状伪足和片状伪足立即回缩。进一步的生长停止，在许多情况下神经突随后回缩。当用1微摩尔河豚毒素（TTX）阻断动作电位时，电刺激未引起形态或生长锥运动性的变化。这些效应取决于刺激的速率、模式和持续时间。阶段性刺激比以恒定频率传递相同数量冲动的刺激更有效。一个重要的新观察结果是，暴露于阶段性刺激数小时的培养物中含有活跃生长的神经突，其生长锥正常，对刺激不敏感。暴露于慢性刺激的神经突中的这种明显适应可能涉及调节钙电导或缓冲的过程。动作电位导致神经突生长停止可能代表一种机制，通过稳定形成适当突触接触的神经突的生长，并导致生长锥从在神经元进入功能活跃回路时未形成适当接触的侧支回缩，从而将哺乳动物发育中的中枢神经系统的形态和功能特征联系起来。
