State-dependent interaction of antiepileptic drugs with voltage-dependent sodium channels and differential regulation of excitatory and inhibitory central neurons

这项拟议的研究的目标是采用生物物理学的方法来了解抗癫痫药物是如何 靶向电压依赖性钠通道的药物通过差异结合到 通道的不同选通状态。这项工作结合了实验室中的两条研究路线， 一种表征了利多卡因、苯妥英、卡马西平等药物的状态依赖相互作用， 和乳糖胺与钠通道的关系，以及另一项研究钠通道的门控如何调节 各种哺乳动物中枢神经元的放电。抗癫痫药物的一个关键特性是差异化 结合到钠通道的不同门控状态，但这如何改变特定类型的 中枢神经元控制病理性神经元活动的机制还知之甚少。例如，更高的亲和力 与开放和失活状态的结合导致使用依赖，作为通道的抑制增加 在动作电位期间，在开放和非激活状态之间循环。然而，这并不容易解释他们的 临床作用，因为使用依赖可能预测对GABA能抑制的更强的抑制 神经元通常以高频放电，而谷氨酸能兴奋性神经元通常 射击要慢一点。我们将研究抗癫痫药物如何与神经元钠通道的门控和 探索状态依赖的结合和解绑如何调节各种兴奋性神经元的放电模式 和抑制性神经元。我们将跟踪初步数据显示卡马西平，苯妥英钠，和 在抑制慢放电谷氨酸能锥体神经元的放电方面，拉莫三嗪均比 快速放电的GABA能神经元。我们将分析这些药物和其他药物(包括新的抗- 癫痫大麻二醇和一种新的、更有效的卡马西平衍生物)与两者的门控相互作用 天然和克隆的钠通道以及由此产生的钠电流的变化如何改变放电 各种兴奋性和抑制性神经元的模式取决于其他 频道。实验设计将动作电位的记录与电压钳相结合。 利用急性分离的脑片上完整的神经元分析潜在的钠电流 神经元和异源表达的克隆通道。一个关键的特点将是研究动作电位 37℃下的点火、通道门控动力学和药物作用。

The goal of the proposed research is to take a biophysical approach to understand how antiepileptic drugs targeted to voltage-dependent sodium channels regulate neuronal firing by differentially binding to different gating states of the channels. The work brings together two lines of research in the laboratory, one characterizing the state-dependent interaction of drugs like lidocaine, phenytoin, carbamazepine, and lacosamide with sodium channels and the other exploring how gating of sodium channels regulates firing of a variety of mammalian central neurons. A key property of antiepileptic drugs is differential binding to different gating states of sodium channels, but how this changes firing of particular kinds of central neurons to control pathological neuronal activity is poorly understood. For example, higher affinity binding to open and inactivated states results in use-dependence, with increased inhibition as channels cycle through open and inactivated states during action potentials. Yet, this does not easily explain their clinical action, because use-dependence might predict more potent inhibition of GABAergic inhibitory neurons, which typically fire at high frequencies, than glutamatergic excitatory neurons, which typically fire more slowly. We will examine how antiepileptic drugs interact with the gating of neuronal sodium channels and explore how state-dependent binding and unbinding regulates the firing patterns of a variety of excitatory and inhibitory neurons. We will follow up preliminary data showing that carbamazepine, phenytoin, and lamotrigine are all more effective in inhibiting firing of slower-firing glutamatergic pyramidal neurons than fast-spiking GABAergic neurons. We will analyze how these drugs and others (including the new anti- epileptic cannabidiol and a novel, more potent carbamazepine derivative) interact with gating of both native and cloned sodium channels and how the resulting changes in sodium current modify the firing patterns of a variety of excitatory and inhibitory neurons in a manner depending on the repertoire of other channels. The experimental design will combine recordings of action potential firing with voltage-clamp analysis of the underlying sodium currents, using intact neurons in brain slice, acutely dissociated neurons, and heterologously expressed cloned channels. A key feature will be to study action potential firing, channel gating kinetics, and drug action at 37 °C.