Ion Channels in Epilepsy and as Targets for Antiepilepti

本项目旨在探索基于抗癫痫药物与神经元离子通道系统相互作用的合理开发新策略。利用细胞电生理记录技术研究了药物对脑切片、培养神经元和转染克隆离子通道亚基基因的异源细胞中神经递质门控和电压激活离子通道的调节作用。在动物模型上进行了相关研究。在本报告所述期间，我们完成了一项研究冷却作为一种癫痫治疗方法的潜力的项目。先前的研究表明，冷却可以终止实验诱导的癫痫样活动，而不会对冷却后的大脑造成伤害，这表明冷却可能是控制顽固性局灶性癫痫发作的一种方法。我们试图确定在体外脑切片模型中应用冷却中止自发性癫痫样放电的最有效方法。我们通过暴露于4-氨基吡啶（4-AP）， 4-AP加二库兰和无镁人工脑脊液（aCSF）在28？34 ? C。在海马或新皮质部位进行细胞外场记录。灌注冷aCSF降低切片温度。以2？5吗?C/s与0.1？1 ? C / s。在所有三个模型和所有记录点，以两种速率冷却都可逆地中止了癫痫样放电。在快速冷却的情况下，小的温度下降在终止排放方面非常有效，只要保持降低的温度水平，这种效果就会持续下去。相比之下，缓慢冷却需要更大的温度下降来抑制放电。随着缓慢冷却，绝对温度降至21度？22吗?C导致事件频率降低90%，但冷却到14？15吗?C被要求终止解雇。我们得出结论，快速冷却可以有效地中止体外癫痫模型中的放电，但所需的温度变化幅度较小。如果冷却速度足够快，抑制癫痫发作活动的实用装置可能只需要诱导小的温度下降。

The objective of this project is to explore new strategies for the rational development of antiepileptic drugs based upon their interaction with neuronal ion channel systems. Cellular electrophysiological recording techniques are used to study drug modulation of neurotransmitter-gated and voltage-activated ion channels in brain slices, cultured neurons and heterologous cells transfected with cloned ion channel subunit genes. Correlative studies are carried out in animal models. In the present reporting period, we completed a project examining the potential of cooling as an epilepy treatment approach. Cooling has been previously shown to terminate experimentally induced epileptiform activity in models of epilepsy without causing injury to the cooled brain, suggesting that cooling could represent an approach to seizure control in intractable focal epilepsies. We sought to determine the most effective way to apply cooling to abort spontaneous epileptiform discharges in in vitro brain slice models. We induced spontaneous epileptiform activity in rat brain slices by exposure to 4-aminopyridine (4-AP), 4-AP plus bicuculline, and magnesium-free artificial CSF (aCSF) at 28?34 ?C. Extracellular field recordings were made at hippocampal or neocortical sites. Slice temperature was reduced by perfusion with cold aCSF. Rapid cooling at rates of 2?5 ?C/s was compared to cooling at slower rates of 0.1?1 ?C/s. Cooling at both rates reversibly aborted epileptiform discharges in all three models and at all recording sites. With rapid cooling, small temperature drops were highly effective in terminating discharges, an effect that was sustained for as long as the reduced temperature level was maintained. In contrast, slow cooling required much larger temperature drops to inhibit discharges. With slow cooling, absolute temperature drops to 21?22 ?C caused a 90% reduction in event frequency, but cooling to 14?15 ?C was required to terminate discharges. We conclude that rapid cooling as effectively aborts discharges in in vitro epilepsy models as does slow cooling, but the magnitude of the temperature change required is less. Practical devices to inhibit seizure activity may only need to induce small temperature drops, if the cooling can be applied sufficiently rapidly.