Seizures, cell death, and mossy fiber sprouting in kainic acid-treated organotypic hippocampal cultures.
Seizures, cell death, and mossy fiber sprouting in kainic acid-treated organotypic hippocampal cultures.
复制标题
红藻氨酸处理的器官型海马培养物中癫痫发作、细胞死亡和苔藓纤维发芽。
DOI：
10.1016/s0306-4522(99)00358-9
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发表时间：
1999
期刊：
影响因子：
3.3
通讯作者：
McNamara,JO
中科院分区：
文献类型：
--
作者：
Routbort,MJ;Bausch,SB;McNamara,JO
齿状颗粒细胞苔藓纤维轴突的出芽是在癫痫人类和实验动物的成熟脑中发现的结构神经元可塑性。苔藓纤维发芽通常出现在实验动物反复发作后，可能有助于癫痫大脑的过度兴奋。苔藓纤维发芽的分子触发器和空间线索的调查一直受到阻碍，缺乏一个最佳的体外模型来研究这种重排。为了使体外模型可行，参与惊厥诱导的苔藓纤维发芽的电路和受体必须位于颗粒细胞附近，而不是依赖于长距离的大脑互连。然而，不知道是否如此。我们在这里报告，应用惊厥剂，红藻氨酸，器官型海马外植体培养诱导癫痫发作，神经元细胞死亡，随后戏剧性苔藓纤维发芽与相似的层状偏好和时间过程中看到的完整的动物。长期（48小时），但不是短暂的（4小时）红藻氨酸治疗引起区域选择性神经元细胞死亡。用红藻氨酸处理的培养物长时间显示出时间和剂量依赖性的颗粒上Timm染色增加，反映了该区域的苔藓纤维神经支配增加。苔藓纤维轴突与神经生物素标记的直接可视化显示，苔藓纤维在红藻氨酸处理的文化表现出显着增加颗粒上轴突分支点和突触终扣。红藻氨酸诱导的细胞死亡和随后的苔藓纤维重组所需的细胞和分子决定因素，因此似乎是固有的海马切片制备，并保存在文化。鉴于功能性抑制剂或药理学试剂可以在该系统中使用的容易性，切片培养物可以提供一个强大的模型，在其中研究参与触发苔藓纤维生长的分子组分和潜在的层状特异性。阐明这些分子通路可能既有明确的苔藓纤维发芽的功能后果的具体效用，以及在理解成熟的中枢神经系统中的突触重组的一般效用。
Sprouting of the mossy fiber axons of the dentate granule cells is a structural neuronal plasticity found in the mature brain of epileptic humans and experimental animals. Mossy fiber sprouting typically arises in experimental animals after repeated seizures and may contribute to the hyperexcitability of the epileptic brain. Investigation of the molecular triggers and spatial cues involved in mossy fiber sprouting has been hampered by the lack of an optimal in vitro model for studying this rearrangement. For an in vitro model to be feasible, the circuitry and receptors involved in convulsant-induced mossy fiber sprouting would have to be localized near the granule cells, rather than being dependent on long-range brain interconnections. However, it is not known whether this is the case. We report here that that application of the convulsant, kainic acid, to organotypic hippocampal explant cultures induces seizures, neuronal cell death, and subsequent dramatic mossy fiber sprouting with a similar laminar preference and time-course to that seen in intact animals. Prolonged (48h) but not transient (4h) kainic acid treatment caused regionally selective neuronal cell death. Cultures treated with kainic acid for a prolonged period displayed a time- and dose-dependent increase in supragranular Timm staining reflective of increased mossy fiber innervation to this area. Direct visualization of mossy fiber axons with neurobiotin-labeling revealed that mossy fibers in kainic acid-treated cultures exhibited a dramatic increase in supragranular axonal branch points and synaptic boutons. The cellular and molecular determinants required for kainic acid-induced cell death and subsequent mossy fiber reorganization thus appear to be intrinsic to the hippocampal slice preparation, and are preserved in culture. Given the ease with which functional inhibitors or pharmacological agents may be utilized in this system, slice cultures may provide a powerful model in which to study the molecular components involved in triggering mossy fiber outgrowth and underlying its laminar specificity. Elucidation of these molecular pathways will likely have both specific utility in clarifying the functional consequences of mossy fiber sprouting, as well as general utility in understanding of synaptic reorganization in the mature central nervous system.