Treatment of status epilepticus

描述(申请人提供)：癫痫持续状态(SE)是一种神经急症，特征是持续时间很长，有时是难治性癫痫发作，与23%的死亡率有关。SE是一种进行性疾病，癫痫发作减少了海马区GABA介导的抑制，进而导致兴奋性神经传递增强和更多癫痫发作。我们建议通过检验兴奋性神经传递增强和突触GABAA受体表达改变维持难治性SE的假说，进一步探讨难治性SE的机制。在之前的资助阶段，NMDA受体拮抗剂被证明可以终止对GABA能药物无效的SE。以低镁暴露培养的大鼠海马神经元，记录兴奋性突触后电流(EPSCs)，观察SE对兴奋性神经传递的影响。在低镁诱导的SE过程中，突触前终末释放谷氨酸的频率和NMDA受体的激活频率增加。这些研究提示了SE过程中兴奋性增强的新机制。我们希望将这些研究扩展到SE的体内模型，并将它们与神经肽甘丙肽治疗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Galanin对Schaffer侧支和CA1区锥体神经元之间谷氨酸能突触的突触前和突触后机制的影响。在其他研究中，用SE处理的动物海马片上的颗粒细胞记录的微小抑制性突触后电流(MlPSCs)的幅度比对照组记录的小，衰减慢。30 nM地西潘对SE处理组小鼠颗粒细胞的mlPSCs无促进作用，但对对照组动物mlPSCs有明显的促进作用。这些研究表明，作为SE的结果，突触中存在的GABAA受体的补体发生了变化。本实验旨在进一步研究SE对齿状颗粒细胞膜片钳记录的抑制性突触后电流(IPSCs)特性的影响。抑制减弱的机制将通过生化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过程中被招募到突触中。在特定目标3中概述的实验，以表征SE对GABAA受体运输的影响。

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.