COBRE: UND: CELLULAR MECHANISMS OF SUBSTANCE P IN EPILEPSY

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。这项研究的长期目标是了解癫痫的细胞机制，并找到更好的治疗策略。P物质（Substance P， SP）是一种分布于外周和中枢神经系统的神经肽。体内实验表明SP与癫痫有关，但其机制尚不清楚。基于1)海马gaba能中间神经元在癫痫发生中起关键作用，2)SP受体在中间神经元中选择性表达，3)SP增强AMPA受体（AMPAR）介导的兴奋性和gabaa受体介导的抑制性突触传递到海马片中间神经元（我们的初步数据），我们提出了SP通过调节海马中间神经元的突触功能来调节癫痫发生的假设。具体来说，我们打算解决以下问题：(1)由于SP通过突触后机制增加AMPA EPSCs，我们将通过峰值非平稳方差分析确定SP增加海马神经元间突触突触后膜上AMPAR打开概率、电导和/或数量的程度。然后，我们将建立SP受体的三个下游信号通路（磷脂酶C、磷脂酶A2和腺苷酸环化酶）在SP效应中的作用。最后，我们将确定内源性释放的SP在增加神经元间AMPAR功能中的作用；(2)由于我们的研究结果表明，SP增加了动作电位依赖性GABAA受体介导的神经元间突触自发IPSCs的频率和幅度，我们将确定SP刺激中间神经元增加GABA释放的离子机制和SP受体的相关信号通路；(3)我们将通过匹罗卡品诱导的海马切片癫痫模型来确定SP是否增加或减少癫痫发作活动，并确定SP受体下游信号通路在癫痫发作中的作用。由于SP受体只分布在海马中间神经元上，我们的研究可能有助于通过选择性调节SP受体在中间神经元上的功能来建立治疗癫痫的新方法。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The long-term goal of the research is to understand the cellular mechanisms underlying epilepsy and to find a better strategy for its treatment. Substance P (SP) is a neuropeptide distributed in both the peripheral and central nervous systems. In vivo experiments show that SP is involved in epilepsy, however, the mechanisms are unknown. Based on the observations that 1) the GABAergic interneurons in hippocampus play a pivotal role in epilepsy, 2) SP receptors are selectively expressed by interneurons and 3) SP enhances both AMPA receptor (AMPAR)-mediated excitatory and GABAA-receptor-mediated inhibitory synaptic transmissions onto interneurons in hippocampal slices (our preliminary data), we propose to test a hypothesis that SP modulates epileptogenesis by regulating the synaptic functions of hippocampal interneurons. Specifically, we intend to address the following issues: (1) Because SP increases AMPA EPSCs by a postsynaptic mechanism, we will determine the extent to which SP increases AMPAR open probability, conductance and/or numbers on postsynaptic membranes at hippocampal interneuron synapses by using peak-scaled non-stationary variance analysis. We will then establish the roles of three downstream signaling pathways (phospholipase C, phospholipase A2 and adenylyl cyclase) of SP receptors in the effects of SP. Finally, we will determine the roles of endogenously released SP in increasing interneuron AMPAR function; (2) Because our results show that SP increases both the frequency and the amplitude of action potential-dependent GABAA receptor-mediated spontaneous IPSCs at interneuron synapses, we will determine the ionic mechanisms by which SP excites interneurons to increase GABA release and the involved signaling pathways of SP receptors; (3) We will determine whether SP increases or decreases seizure activity using a pilocarpine-induced epilepsy model in hippocampal slices and determine the roles of the signaling pathways downstream of SP receptors in seizures. Because SP receptors are exclusively distributed on hippocampal interneurons, our research may help establish a novel approach for treating epilepsy by selectively modulating SP receptor functions on interneurons.