Progressive seizure-induced cardiorespiratory dysfunction in a novel mutant rat model of seizure disorder

项目摘要 全球有超过5000万人患有癫痫。目前的抗癫痫药物（AEDs）不能预防 这些患者中约30%发生癫痫发作，导致不受控制或难治性癫痫。不幸的是，这些病人 癫痫猝死（SUDEP）的风险极高，这是导致死亡的主要原因。 这个cohort。基于具有里程碑意义的SUDEP研究，目前的假设是，反复发作引起极端的癫痫发作。 通过对调节生命活动的神经网络的负面影响， 呼吸、心率和血压等功能。然而，仍不清楚反复发作 从根本上影响脑干内的心肺控制网络，以及这些机制是什么？ 重要系统在SUDEP中失效。在这里，我们的目的是描述重复性的病理生理后果。 在钾通道基因（kcnj 16; SSkcnj 16-/-大鼠）中具有已知突变的新型大鼠模型中， 一种特定的轻微强度的声音容易并可重复地引起全身强直阵挛性发作 （一般贸易条件下）。声音诱导的SSkcnj 16-/-大鼠GTCS导致了与上述相似的刻板模式的事件 在癫痫患者中，包括发作后全身性EEG抑制和呼吸暂停，其次是呼吸频率 (RR)和心率（HR）抑制。反复癫痫发作（1次/天，持续10天）导致：1）术后增强， RR和HR的发作抑制，对缺氧和高碳酸血症挑战的缓解反应降低，以及 约33%的大鼠意外死亡。SSkcnj 16-/-大鼠反复暴露于 癫痫发作显示炎症和腺苷（ADO）失调的时间依赖性增加的证据 和5-羟色胺（5-HT）-心肺神经网络的两种强有力的调节剂。最后， 用SSRI（氟西汀）增加5-HT可防止反复发作后RR的进行性抑制， 癫痫发作在这里，我们将测试我们的中心假设，反复癫痫发作导致进行性脑干 病理学由神经炎症引发，并由ADO和5-HT功能障碍介导，导致 SUDEP中的心肺抑制和/或衰竭。利用这种新型突变大鼠的拟议研究 模型将提供：1）对以下疾病的进行性病理生理反应的全面表征： 反复听源性癫痫发作和导致意外死亡的事件序列（目的1），2）确定 危重心肺疾病中炎症和/或神经调节通路功能障碍的机制 脑干核团受到反复发作的负面影响（目的2），和3）功能测试我们的干预措施， 通过阻断神经炎症或调节ADO或5-HT系统活性， 反复发作（目标3）。我们将利用成熟和尖端技术的组合， 前所未有的分子，细胞和系统水平的见解的病理生理后果 反复发作对重要控制系统的影响，以确定治疗干预的新靶点， 预防或减轻人类癫痫患者发生SUDEP的风险。

Project Summary More than 50 million people suffer from epilepsy globally. Current anti-epileptic drugs (AEDs) cannot prevent seizures in ~30% of these patients, leading to uncontrolled or refractory epilepsy. Unfortunately, these patients are at extreme risk of Sudden Unexpected Death in Epilepsy (SUDEP), which is the leading cause of death in this cohort. Based on landmark SUDEP studies, the current hypothesis is that recurrent seizures induce extreme cardiorespiratory suppression and/or failure through negative effects on the neural networks that regulate vital functions such as breathing, heart rate and blood pressure. However, it remains unclear how repeated seizures fundamentally affect cardiorespiratory control networks within the brainstem, and by what mechanisms these vital systems fail in SUDEP. Here we aim to characterize the pathophysiologic consequences of repeated seizures in a novel rat model with a known mutation in a potassium channel gene (kcnj16; SSkcnj16-/- rats), in which a specific sound of mild intensity readily and reproducibly causes generalized tonic-clonic seizures (GTCSs). Sound-induced GTCSs in SSkcnj16-/- rats led to a stereotypic pattern of events similar to that described in epilepsy patients, including post-ictal generalized EEG suppression and apnea, followed by respiratory rate (RR) and heart rate (HR) suppression. Repeated seizures (1/day for up to 10 days) led to: 1) augmented post- ictal suppression of RR and HR, reduced ventilatory responses to hypoxic and hypercapnic challenges, and unexpected mortality in ~33% of these rats. Brainstem tissue analyses of SSkcnj16-/- rats exposed to repeated seizures showed evidence of time-dependent increases in inflammation and dysregulation of adenosine (ADO) and serotonin (5-HT) – two powerful modulators of cardiorespiratory neural networks. Finally, pharmacologically augmenting 5-HT with an SSRI (fluoxetine) prevented the progressive suppression of post-ictal RR with repeated seizures. Herein we will test our central hypothesis that repeated seizures cause a progressive brainstem pathology initiated by neuroinflammation and mediated by ADO and 5-HT dysfunction leading to cardiorespiratory suppression and/or failure in SUDEP. The proposed studies utilizing this novel mutant rat model will provide: 1) a comprehensive characterization of the progressive pathophysiological responses to repeated audiogenic seizures, and sequence of events leading to unexpected death (Aim 1), 2) identified mechanisms of dysfunction in inflammatory and/or neuromodulatory pathways within critical cardiorespiratory brainstem nuclei negatively affected by repeated seizures (Aim 2), and 3) interventions that functionally test our hypothesis by blocking neuroinflammation or modulating ADO or 5-HT system activity on the backdrop of repeated seizures (Aim 3). We will utilize a combination of established and cutting-edge technologies to provide unprecedented molecular, cellular and systems-level insights into the pathophysiological consequences repeated seizures on vital control systems in order to identify novel targets for therapeutic interventions aimed at preventing or mitigating the risk of SUDEP in human epilepsy patients.