Interneurons and Epilepsy in Dlx1 Mutant Mice

描述（申请人提供）：抑制性中间神经元合成GABA，在中枢神经系统中起重要的调节作用。最近的观察表明，这些中间神经元的发育需要一个Dlx转录因子家族。在我们实验室的研究中（Cobos et al. 2005），研究证明缺乏Dlx1的小鼠逐渐失去皮层和海马中间神经元的一个亚类，导致突触抑制减少和癫痫。这种新颖的中间神经元缺陷迟发性癫痫模型提供了一个独特的机会，可以精确定义中间神经元在癫痫发生中的作用，并最终测试治疗干预来中断或废除这一过程。为了回应最近的NINDS“基准”，我们在这里提出了一些实验，将研究Dlx1缺陷（以及随后的中间神经元丢失）如何改变网络兴奋性，并测试使用GABA祖细胞的潜在治疗干预。技术将包括使用体外保存的急性脑切片和应用可视化膜片钳方法来研究海马中间神经元及其相关回路的生理功能。视频脑电图监测和细胞移植技术也将被应用。提出了三个具体目标：(i)确定Dlx1是否需要中间神经元功能，（ii）确定Dlx1突变小鼠中存活的中间神经元的突触输入是否被破坏，以及（iii）确定GABA祖细胞移植是否减少Dlx1突变小鼠的癫痫发作活动。我们的结果有望提供关于中间神经元在癫痫中的作用的关键信息，并可能直接证明GABA祖细胞治疗癫痫发作的潜力。

DESCRIPTION (provided by applicant): Inhibitory interneurons synthesize GABA and play a critical regulatory role in the central nervous system. Recent observations suggest that development of these interneurons requires a family of Dlx transcription factors. In studies from our laboratory (Cobos et al. 2005), it was demonstrated that mice lacking Dlx1 progressively lose a sub-class of cortical and hippocampal interneurons resulting in reduced synaptic inhibition and epilepsy. This novel model of interneuron-deficient, late-onset epilepsy offers a unique opportunity to precisely define the role of interneurons in epileptogenesis, and ultimately test therapeutic interventions to interrupt or abrogate this process. In response to recent NINDS "benchmarks", we here propose experiments that will examine how Dlx1 deficiency (and subsequent interneuron loss) alters network excitability, and test a potential therapeutic intervention using GABA progenitor cells. Techniques will involve use of acute brain slices maintained in vitro, and application of visualized patch clamp methods to study the physiological function of hippocampal interneurons and their associated circuits. Video-EEG monitoring and cell grafting techniques will also be applied. Three specific aims are proposed: (i) determine whether Dlx1 is required for interneuron function, (ii) determine whether synaptic input to surviving interneurons is disrupted in Dlx1 mutant mice, and (iii) determine whether GABA progenitor cell grafts reduce seizure activity in Dlx1 mutant mice. Our results promise to provide critical information about the role of interneurons in epilepsy and may provide a direct demonstration of the potential for GABA progenitor cells to treat seizures. PUBLIC HEALTH RELEVANCE: Epilepsy is a common neurological disorder afflicting nearly 3 million Americans. Loss or reduction of inhibitory synaptic transmission in hippocampal and cortical circuits is one potential mechanism resulting in the emergence of epilepsy. Using a mouse mutant lacking inhibitory nerve cells, and a cell grafting strategy to generate new inhibitory nerve cells, we will examine the mechanisms underlying epilepsy and a potential treatment.