Excitatory synaptic transmission onto hippocampal interneurons

海马中间神经元的兴奋性突触传递

• 批准号: 8220870
• 负责人: MATTHEW E FRERKING
• 金额: $ 32.59万
• 依托单位: OREGON HEALTH & SCIENCE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-02-15 至 2014-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8220870
• 关键词: AMPA Receptors; Affect; Affinity; Binding Proteins; Cells; Epilepsy; Excitatory Synapse; Genetic; Glutamate Receptor; Glutamate Transporter; Glutamates; Goals; Hippocampus (Brain); Interneurons; Kainic Acid Receptors; Kinetics; Mediating; Methods; Microscopy; Morphology; N-Methyl-D-Aspartate Receptors; Nature; Neurons; Peptides; Physiologic pulse; Physiological; Play; Population Heterogeneity; Process; Property; Proteins; Pyramidal Cells; Receptor Activation; Recruitment Activity; Regulation; Research; Role; Scaffolding Protein; Seizures; Signal Transduction; Slice; Synapses; Synaptic Transmission; Synaptic plasticity; System; Testing; Therapeutic; base; extracellular; genetic manipulation; information processing; inhibitory neuron; interest; millisecond; neural circuit; neurochemistry; operation; patch clamp; postsynaptic; prevent; public health relevance; receptor; receptor expression; response; selective expression; transmission process; uptake; voltage clamp

DESCRIPTION (provided by applicant): The activity and function of cortical circuits depend on the interplay between two interconnected sets of cells: excitatory principal neurons and inhibitory interneurons. Inhibitory interneurons play a critical role in preventing the circuit excitability that leads to epileptiform activity, and also are involved in a number of other processes as well, including regulation and synchronization of firing in principal neurons, release of neuromodulatory peptides, and somatodendritic inhibition of principal neurons. These functions are triggered by interneuronal activation, which occurs through excitatory synaptic transmission onto these cells. This excitatory transmission is primarily glutamatergic, and the excitatory postsynaptic current (EPSC) is mediated largely by ionotropic glutamate receptors of the AMPA receptor (AMPAR) and kainate receptor (KAR) subtypes. We have studied the AMPAR/KAR EPSCs onto hippocampal interneurons located in stratum radiatum and stratum lacunosum-moleculare (SR/SLM). We have found that the EPSC generated by extracellular stimulation has two kinetically distinct components: a rapid, large EPSC that is mediated by AMPARs and is generally similar to AMPAR EPSCs seen throughout the CNS; and a slow, small EPSC that is mediated by both KARs and AMPARs. This slow EPSC lasts for hundreds of milliseconds, which is completely unexpected based on the kinetics of heterologously expressed AMPARs/KARs in response to brief pulses of glutamate. The AMPAR component of the slow EPSC, but not the KAR component, can also be massively potentiated by inhibition of glutamate uptake. These results suggest that the kinetics of the slow EPSC must be determined by a prolonged glutamate transient, or by factors within the interneuron that alter the kinetics of native receptors compared to heterologously expressed receptors, and that the answer may differ depending on the receptor subtype involved and the efficacy of uptake mechanisms. In the proposed research, we will examine the mechanisms underlying the slow EPSC. We will use whole-cell voltage-clamp recording of SR/SLM interneurons in hippocampal slices to record the EPSC, and a variety of pharmacological and genetic manipulations to affect glutamate release, reception, and uptake. Our specific aims are: 1) to test whether the slow AMPAR EPSC is generated by glutamate spillover; 2) to determine whether the receptors underlying the slow EPSC have kinetics that are dictated by receptor subunit composition or interactions with scaffolding proteins; and 3) to define the role of glutamate uptake mechanisms in regulating the slow EPSC. PUBLIC HEALTH RELEVANCE: This project will identify mechanisms of regulating the activity of hippocampal interneurons, which prevent hyperexcitability under normal conditions. This research will allow us to evaluate the possibility of developing therapeutic strategies to control seizure initiation or propagation by manipulating excitatory transmission onto these interneurons.

描述（由申请人提供）：皮层回路的活动和功能取决于两组相互连接的细胞之间的相互作用：兴奋性主神经元和抑制性中间神经元。抑制性中间神经元在防止导致癫痫样活动的回路兴奋性方面发挥关键作用，并且还参与许多其他过程，包括主要神经元中放电的调节和同步，神经调节肽的释放以及主要神经元的体树突抑制。这些功能由神经元间激活触发，神经元间激活通过兴奋性突触传递到这些细胞上而发生。这种兴奋性传递主要是谷氨酸能的，并且兴奋性突触后电流（EPSC）主要由AMPA受体（AMPAR）和红藻氨酸受体（KAR）亚型的离子型谷氨酸受体介导。 我们研究了海马放射层和腔隙分子层（SR/SLM）中间神经元的AMPAR/KAR EPSCs。我们已经发现，由细胞外刺激产生的EPSC具有两种动力学上不同的组分：由AMPAR介导的快速、大的EPSC，通常与在整个CNS中观察到的AMPAR EPSC相似;以及由KAR和AMPAR介导的缓慢、小的EPSC。这种缓慢的EPSC持续数百毫秒，这是完全出乎意料的基础上异源表达的AMPAR/KAR的动力学响应于短暂的谷氨酸脉冲。慢EPSC的AMPAR组分，而不是KAR组分，也可以通过抑制谷氨酸摄取而大大增强。这些结果表明，慢EPSC的动力学必须由一个长期的谷氨酸瞬变，或由interneuron内的因素，改变天然受体的动力学相比，异源表达的受体，答案可能会有所不同，这取决于受体亚型和吸收机制的功效。 在这项研究中，我们将研究慢EPSC的机制。我们将使用全细胞电压钳记录海马切片中的SR/SLM中间神经元来记录EPSC，以及各种药理学和遗传学操作来影响谷氨酸的释放、接收和摄取。我们的具体目标是：1）测试慢AMPAR EPSC是否由谷氨酸溢出产生; 2）确定慢EPSC背后的受体是否具有由受体亚基组成或与支架蛋白的相互作用决定的动力学;和3）确定谷氨酸摄取机制在调节慢EPSC中的作用。公共卫生关系：这个项目将确定调节海马中间神经元活动的机制，防止在正常条件下的过度兴奋。这项研究将使我们能够评估开发治疗策略的可能性，通过操纵兴奋性传递到这些中间神经元来控制癫痫发作的开始或传播。