Treatment of status epilepticus

描述（由申请人提供）： 癫痫持续状态（SE）是一种神经系统急症，其特征是持续时间很长，有时是难治性癫痫发作，死亡率为23%。SE是一种进行性病症，其中癫痫发作减少海马中GABA介导的抑制，这反过来导致兴奋性神经传递增强和更多癫痫发作。我们建议进一步研究难治性SE的机制，通过测试的假设，增强兴奋性神经传递和改变表达GABAA受体在突触维持难治性SE。在上一个资助期，已证明NMDA受体拮抗剂可终止GABA能药物难治性SE。在体外模型中，通过将海马培养物暴露于低镁并记录兴奋性突触后电流（EPSC）来检查SE对兴奋性神经传递的影响。在低镁诱导的SE过程中，EPSCS（突触前末梢谷氨酸释放）和NMDA受体激活的频率增加。这些研究提出了一种新的机制，增加兴奋性在SE。我们希望将这些研究扩展到SE的体内模型，并将其与神经肽甘丙肽（galanin）治疗SE的新方法联系起来。具体目标1中概述的实验表征了SE和抗惊厥剂甘丙肽对海马中Schaffer侧支和CA1锥体神经元之间的突触能突触中的突触前和突触后机制的影响。在其他研究中，从SE处理的动物制备的海马切片中的颗粒细胞记录的微型抑制性突触后电流（mlPSC）的幅度较小，衰减较慢，比对照组记录的幅度更小。从SE处理的动物的颗粒细胞记录的这些mlPSC没有被30 nM地西泮增强，但是来自对照动物的那些被强烈增强。这些研究表明，作为SE的结果，存在于突触处的GABAA受体的补体发生了变化。在具体目标2中提出的实验试图进一步表征SE对通过膜片钳记录从齿状颗粒细胞记录的抑制性突触后电流（IPSC）的性质的影响。抑制减弱的机制将通过生物化学和神经解剖学研究进一步探索。初步研究表明，神经元调节GABAA受体的内吞速率，突触外受体可能在SE期间被募集到突触中。具体目标3中概述的实验旨在表征SE对GABAA受体转运的影响。

DESCRIPTION (provided by applicant): Status epilepticus (SE) is a neurological emergency characterized by very prolonged, sometimes refractory seizures, and is associated with a 23% mortality. SE is a progressive condition where seizures reduce GABA-mediated inhibition in the hippocampus, which in turn leads to enhanced excitatory neurotransmission and more seizures. We propose to further investigate the mechanisms refractory SE, by testing the hypothesis that enhanced excitatory neurotransmission and altered expression GABAA receptors at synapses maintain refractory SE. In the previous funding period, NMDA receptor antagonists were demonstrated to terminate SE refractory to GABAergic agents. The effect of SE on excitatory neurotransmission was examined in an in vitro model, by exposing hippocampal cultures to low magnesium, and recording excitatory post synaptic currents (EPSCs). There was increased frequency of EPSCS (glutamate release from presynaptic terminals) and activation of NMDA receptors during low-magnesium induced SE. These studies suggested a novel mechanism of increased excitability during SE. We wish to extend these studies to in vivo models of SE and link them to a novel treatment of SE, with the neuropeptide galanin. Experiments outlined in specific aim 1 characterize the effects of SE and anticonvulsant galanin on pre and post synaptic mechanisms in the glutamatergic synapses between Schaffer collaterals and CA1 pyramidal neurons in the hippocampus. In other studies, miniature inhibitory postsynaptic currents (mlPSCs) recorded from granule cells in hippocampal slices prepared from SE-treated animals were smaller in amplitude and slower in decay than those recorded from controls. These mlPSCs recorded from granule cells of SE-treated animals were not enhanced by 30 nM diazepam but those from control animals were robustly enhanced. These studies suggested that the complement of GABAA receptors present at the synapse had changed as a consequence of SE. Experiments proposed in specific aim 2 seek to further characterize the effect of SE on the properties of inhibitory postsynaptic currents (IPSCs) recorded from dentate granule cells by means of patch clamp recordings. The mechanisms of diminished inhibition will be explored further by biochemical and neuroanatomical studies. Preliminary studies suggest that neuronal modulates the rate of endocytosis of GABAA receptors and extrasynaptic receptors may be recruited into synapses during SE. Experiments outlined in specific aim 3 To characterize the effect of SE on GABAA receptor trafficking.