LOCAL INTERACTIONS BETWEEN HIPPOCAMPAL NEURONS

描述(调查人员摘要)：尽管数量可观 有关癫痫发作的潜在机制的信息可用 慢性癫痫发生的细胞基础不是 明白了。突触和非突触机制都可能 与癫痫发作的超同步性有关 颞叶癫痫。经红藻氨酸处理的大鼠将被用作 用动物模型研究这些神经元通讯机制是如何 参与与颞叶癫痫相关的癫痫发作。 行为、电生理和解剖学研究将 在红藻氨酸治疗后2-3个月进行，当动物表现出许多 颞叶癫痫的临床特点。同时使用体内和 体外电生理记录与随后的解剖 在同一动物身上进行分析，我们将评估突触 重组(例如，改变的反复兴奋和/或抑制) 和/或非突触机制的变化对 海马区癫痫的发生。需要检验的两个假设是- 新的经常性兴奋回路和/或增强的非突触机制 参与或调节海马区癫痫发作的增加 颞叶癫痫的易感性。 齿状颗粒在体场电位的慢性记录 将使用细胞和同步视频监控来评估 自由行为红藻氨酸对大鼠海马区癫痫易感性的影响 老鼠。将使用成对脉冲在体内评估突触抑制 穿透路径刺激。“自发的”发作间歇期棘波和 海马区癫痫发作也将在体内进行评估。细胞内和 海马齿状颗粒细胞的细胞外记录 然后进行切片以确定细胞的变化。 来自相同红藻氨酸处理大鼠的突触和非突触机制。 细胞外刺激、谷氨酸微量应用和双重作用 细胞内的记录将被用来评估在 反复的抑制和/或兴奋会增加癫痫发作 齿状回的易感性。使用HIGH进行类似的实验 胞外[K~]、低胞外ICa2+及沐浴应用 氨基酸受体拮抗剂将确定其贡献 癫痫发生的非突触机制。关于齿状突起的其他研究 红藻氨酸处理的大鼠发芽前和海马区的脑回 发芽后损毁的大鼠将提供额外的测试 突触重组在损伤中起关键作用的假说- 诱发性癫痫。这些体外实验将表明 突触和非突触机制慢性改变癫痫发作 红藻氨酸治疗后大鼠海马区癫痫发生的易感性 老鼠。对这些问题的批判性分析将提供重要的新 关于这些机制在慢性疾病中的作用的信息 癫痫的发生，这将反过来导致更好地理解 如何治疗颞叶癫痫。

DESCRIPTION (Investigator's Abstract): Although considerable information is available about the mechanisms underlying seizure generation, the cellular basis of chronic epileptogenesis is not understood. Both synaptic and nonsynaptic mechanisms are likely to contribute to the hypersynchronization characteristic of seizures in temporal lobe epilepsy. The kainate treated rat will be used as an animal model to study how these mechanisms of neuronal communication participate in the seizures associated with temporal-lobe epilepsy. Behavioral, electrophysiological and anatomical studies will be undertaken 2-3 mo after kainate treatment, when the animals show many of the clinical features of temporal-lobe epilepsy. Using both in vivo and in vitro electrophysiological recording with subsequent anatomical analysis in the same animal, we will evaluate whether synaptic reorganization (e.g., altered recurrent excitation and/or inhibition) and/or changes in nonsynaptic mechanisms contribute significantly to hippocampal epileptogenesis. The two hypotheses to be tested are-that new recurrent excitatory circuits and/or enhanced non-synaptic mechanisms contribute to or mediate the increased hippocampal seizure susceptibility of temporal-lobe epilepsy. Chronic in vivo recording of field potentials from the dentate granule cells and simultaneous video monitoring will be used to evaluate hippocampal seizure susceptibility in freely-behaving kainate-treated rats. Synaptic inhibition will be evaluated in vivo with paired-pulse perforant-path stimulation. "Spontaneous" interictal spikes and hippocampal seizures will also be assessed in vivo. lntracellular and extracellular recordings from dentate granule cells in hippocampal slices will then be undertaken to determine cellular alterations in synaptic and nonsynaptic mechanisms from the same kainate-treated rats. Extracellular stimulation, glutamate microapplication, and dual intracellular recordings will be used to evaluate whether changes in recurrent inhibition and/or excitation have increased seizure susceptibility in the dentate gyrus. Similar experiments using high extracellular [K~], low extracellular ICa2+] and bath application of amino acid receptor antagonists will identify the contribution of nonsynaptic mechanisms to epileptogenesis. Other studies on the dentate gyrus of kainate-treated rats before sprouting and of hippocampal- lesioned rats after sprouting will provide additional tests of the hypothesis that synaptic reorganization plays a critical role in damage- induced epilepsy. These in vitro experiments will indicate whether synaptic and nonsynaptic mechanisms chronically alter seizure susceptibility during hippocampal epileptogenesis in the kainate-treated rat. A critical analysis of these issues will provide important new information about the role of these mechanisms in chronic epileptogenesis, which will in turn lead to a better understanding of how to treat temporal-lobe epilepsy.