Testing the excitability of inhibitory neurons

描述（由申请人提供）：本研究的长期目标是研究控制皮层中间神经元兴奋性的稳态机制。强直活性GABA-A受体是一种强有力的体内平衡调节剂。因此，本提案提出的研究的总体目标是抑制强直电流（l-Tonic）和这些专门的GABA-A受体的表达和调节。采用全细胞膜片钳切片电生理、敲除小鼠和免疫细胞化学技术相结合的方法研究了小鼠体感桶皮层第4层的强直抑制作用。这项提议有两个主要目标。第一个目标是确定细胞类型特异性的基础水平和这种强直抑制背后的机制。我们的初步数据表明，两种主要的抑制性细胞类型（常规非锥体尖峰（RSNP）和低阈值尖峰（LTS））被大张力电流抑制，至少部分是由含有6亚基的受体介导的。第二个目标是确定l-Tonic的活动水平依赖性、稳态变化。剃须会改变第4层桶状皮质的活动水平。本文提出的第二组实验检验了这对皮质神经元的兴奋性和强直性抑制的影响。源于这一应用的实验集中于控制皮层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，使我们能够研究细胞兴奋性的使用依赖性降低。了解控制兴奋性的基本机制（例如，体内平衡）将有助于理解疾病的发展过程。

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.