Mechanisms and consequences of neuronal stretch injury in vitro differ with the model of trauma
Mechanisms and consequences of neuronal stretch injury in vitro differ with the model of trauma
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DOI：
10.1089/neu.2006.23.193
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发表时间：
2006-02-01
影响因子：
4.2
通讯作者：
Meaney, DF
中科院分区：
文献类型：
--
作者：
Geddes-Klein, DM;Schiffman, KB;Meaney, DF
在创伤性脑损伤（TBI）期间发生的脑变形导致整个脑组织的复杂应变分布。最近，已经开发了许多神经元损伤的体外模型以简化在TBI期间发生的力学。我们假设施加到神经元上的机械损伤的类型将显著改变神经元对损伤的反应的机制和严重性。在这项研究中，原代皮层神经元培养在弹性基板上，并进行分级水平（0%，10%，30%，50%）的单轴（细胞在一个方向拉伸）或双轴（细胞同时在两个方向拉伸）拉伸。我们发现，在任一损伤范例中拉伸的神经元表现出细胞内游离钙（[Ca 2 +]（i））的立即增加，但[Ca 2 +]（i）上升的幅度在双轴拉伸神经元中比单轴拉伸神经元高出近一个数量级。此外，虽然单轴拉伸后的[Ca 2 +]（i）瞬变被特异性通道拮抗剂（APV，CNQX，尼莫地平，TTX）阻断，但在双轴拉伸神经元中持续存在大量[Ca 2 +]瞬变。我们的理论是，双轴拉伸后额外的钙流入通过膜中形成的非特异性孔/裂缝进入，因为双轴拉伸神经元表现出显著的羧基荧光素吸收，一种通常不渗透细胞膜的分子。尽管[Ca 2 +]（i）瞬变很大，但两种损伤特征均未导致损伤后24小时内的死亡。然而，有趣的是，与对照和双轴拉伸的神经元相比，单轴拉伸的神经元在创伤后24小时在NMDA刺激后表现出增强的[Ca+2]（i）内流。这些数据指出，机械损伤的类型将影响体外急性损伤机制，可能导致对潜在继发性兴奋性毒性损伤机制的反应差异，并强调需要进一步研究这些机械条件如何单独影响机械损伤后的细胞命运。
The deformation to the brain that occurs during traumatic brain injury (TBI) results in a complex strain distribution throughout the brain tissue. Recently, many in vitro models of neuronal injury have been developed to simplify the mechanics which occur during TBI. We hypothesized that the type of mechanical insult imparted onto neurons would significantly alter both the mechanism and severity of the neuronal response to injury. In this study, primary cortical neurons were cultured on an elastic substrate and subjected to graded levels (0%, 10%, 30%, 50%) of either uniaxial (cells stretched in one direction only) or biaxial (cells simultaneously stretched in two directions) stretch. We found that neurons stretched in either injury paradigm exhibited immediate increases in intracellular free calcium ([Ca2+](i)), but the magnitude of the [Ca2+](i) rise was nearly an order of magnitude higher in biaxially stretched neurons compared to uniaxially stretched neurons. Moreover, while the [Ca2+](i) transient after uniaxial stretch was blocked with specific channel antagonists (APV, CNQX, nimodipine, TTX), a substantial [Ca2+], transient persisted in biaxially stretched neurons. We theorized that the additional calcium influx after biaxial stretch entered through nonspecific pores/tears formed in the membrane, since biaxially stretched neurons exhibited significant uptake of carboxyfluorescein, a molecule typically impermeant to cell membranes. Despite the large [Ca2+](i) transients, neither injury profile resulted in death within 24 h of injury. Interestingly, though, uniaxially stretched neurons exhibited enhanced [Ca+2](i) influx following NMDA stimulation 24 h after trauma, compared to both control and biaxially stretched neurons. These data point out that the type of mechanical insult will influence the acute mechanisms of injury in vitro, can cause differences in the response to potential secondary excitotoxic injury mechanisms, and emphasizes the need to further study how these mechanical conditions can separately affect cell fate following mechanical injury.