Testing the excitability of inhibitory neurons

描述(申请人提供)：这项研究的长期目标是研究控制皮质中间神经元兴奋性的稳态机制。张力活跃的GABA-A受体可以成为体内平衡的强大调节器。因此，这项研究的总体目标是表达和调节这种抑制性紧张性电流(L-张力)和这些特殊的GABA-A受体。结合全细胞膜片钳切片电生理学、基因敲除小鼠和免疫细胞化学技术，研究了小鼠躯体感觉桶皮质第四层的紧张性抑制。这项提议有两个主要目标。第一个目标是确定这种紧张性抑制的细胞类型特定的基础水平和机制。我们的初步数据表明，两种主要的抑制细胞类型(规则尖峰非锥体细胞(RSNP)和低阈值尖峰细胞(LTS))被大的紧张性电流抑制，至少部分由含有6-亚基的受体介导。第二个目标是确定活动水平依赖的、动态平衡的L张力变化。摘除胡须改变了第四层桶状皮质的活动水平。这里提出的第二组实验考察了这对大脑皮层神经元兴奋性和紧张性抑制的影响。源于这一应用的实验专注于控制皮质中间神经元内在可塑性的基本机制，因此适用于广泛的疾病状态。我们使用一种感觉系统，使我们能够研究依赖使用的细胞兴奋性的降低。了解控制兴奋性(例如，稳态)的基本机制将为理解疾病的发展过程提供洞察力。

DESCRIPTION (provided by applicant): The long term goal of this research is to study homeostatic mechanisms that control the excitability of cortical interneurons. Tonically active GABA-A receptors can be a powerful regulator of homeostasis. The overall goal for the research presented in this proposal therefore is the expression and regulation of this inhibitory tonic current (l-Tonic) and these specialized GABA-A receptors. A combination of whole-cell patch-clamp slice electrophysiology, knockout mice, and immunocytochemistry techniques are employed to study tonic inhibition in layer 4 of the mouse somatosensory barrel cortex. There are two primary goals of this proposal. The first goal is to identify cell-type specific basal levels of and mechanisms behind this tonic inhibition. Our preliminary data suggests that two major inhibitory cell types (the regular spiking non pyramidal (RSNP) and the low threshold spiking (LTS)) are inhibited by large tonic currents, mediated at least in part by 6-subunit containing receptors. The second goal is to identify activity- level-dependent, homeostatic, changes in l-Tonic. Whisker plucking alters the level of activity in layer 4 barrel cortex. The second set of experiments proposed here examines the effects of this on excitability and tonic inhibition in cortical neurons. The experiments stemming from this application focus on a basic mechanism that controls the intrinsic plasticity of cortical interneurons and as such is applicable to a broad spectrum of disease states. We use a sensory system that allows us to study use-dependent reductions in cell excitability. Understanding the basic mechanisms that control excitability (e.g., homeostasis) will provide insight for understanding the developmental process of disease.