GABA signaling in the nTS and cardiorespiratory responses to hypoxia

维持兴奋性谷氨酸和抑制性GABA信号传导的平衡对于体内平衡和代谢是至关重要的。 对缺氧做出适当的反应我们以前的研究建立了谷氨酸信号在 孤束核（nTS），颈动脉体感觉整合的第一个中心部位，在 慢性间歇性缺氧（CIH）。然而，γ-氨基丁酸的具体贡献， 谷氨酸信号，在夸张的兴奋是未知的。我们目前的目标是解决这些知识 间隙，并确定抑制性GABA信号传导有助于CIH后nTS过度兴奋的程度。 GABA信号传导受GABA释放、受体（GABARs）激活、氯离子（Cl-） 平衡电位由Cl-共转运蛋白（NKCC 1和KCC 2）设定，星形胶质细胞通过 转运蛋白（GATs）。鉴于目前的文献和我们的支持初步数据，我们的总体 一种假设是CIH通过减少GABA信号传导而使nTS活性转变为过度兴奋状态， GABA抑制和星形胶质细胞GAT活性增加。减少GABA提示Glu和GABA的平衡 信令，以及它们对彼此的影响（即，串扰），朝向更大的激励，以最终增加 化学反射反应目的1将确定GABA信号在CIH中改变以增加nTS的程度 兴奋性工作假设：减少GABA抑制增加nTS兴奋性和心肺功能 在CIH中的作用GABA抑制在CIH中减弱，这是由于Glu上的GABA释放或GABAR减少 神经元、改变的Cl-转运和/或增强的星形胶质细胞GAT。目标2将定义幅度nTS GABA 星形胶质细胞GABA转运蛋白影响CIH中Glu信号传导，以控制神经元和心肺功能 功能工作假设：CIH后，GABA-Glu平衡向兴奋方向转移，部分原因是 GAT功能，最终增加nTS兴奋性和心肺功能。在本申请中，我们 将采用多方面、协同和综合的办法。我们将使用一系列技术，包括 单细胞电生理学、活细胞成像、DREADD细胞操作和分子生物学， 最终破译生理功能。我们还将利用AAV表达和Cre-技术在转基因植物中进行研究。 大鼠，允许从单个细胞到整个动物的GABA神经元的特定记录和操作。 每一种技术都直接补充了另一种技术，从而实现了无与伦比的研究深度。所有这些 技术允许系统的垂直研究和细致的细胞研究。完成后 提出的研究，我们希望确定的意义和机制升高的nTS活动，由于 减少GABA信号传导，导致IH疾病中的心肺功能异常。

Maintaining the balance of excitatory glutamate and inhibitory GABA signaling is critical for homeostasis and generating proper reflexes in response to hypoxia. Our previous studies established glutamate signaling in the nucleus tractus solitarii (nTS), the first central site for carotid body sensory integration, is exaggerated after chronic intermittent hypoxia (CIH). However, the specific contribution of GABA, which counter-balances glutamate signaling, in the exaggerated excitation is unknown. Our current goal is to address this knowledge gap and determine the extent that inhibitory GABA signaling contributes to overexcitation of the nTS after CIH. GABA signaling is controlled or modulated by GABA release, receptor (GABARs) activation, the chloride (Cl-) equilibrium potential that is set by Cl- co-transporters (NKCC1 and KCC2), and astrocytic GABA uptake via transporters (GATs). Given the present literature and our supporting preliminary data, our overarching hypothesis is that CIH shifts nTS activity to an overexcited state due to attenuated GABA signaling via reduced GABA inhibition and increased astrocyte GAT activity. Reduced GABA tips the balance of Glu and GABA signaling, and their influence on each other (i.e., cross-talk), towards greater excitation to ultimately increase chemoreflex responses. Aim 1 will determine the extent GABA signaling is altered in CIH to increase nTS excitability. Working hypothesis: Reduced GABA inhibition increases nTS excitability and cardiorespiratory function in CIH. GABA inhibition is attenuated in CIH due to reduced GABA release or GABARs on Glu neurons, altered Cl- transport and/or augmented astrocyte GAT. Aim 2 will define the magnitude nTS GABA and astrocyte GABA transporters influence Glu signaling in CIH to control neuronal and cardiorespiratory function. Working hypothesis: GABA-Glu balance is shifted towards excitation after CIH, in part due to altered GAT function, to ultimately to increase nTS excitability and cardiorespiratory function. In this application, we will utilize a multi-faceted, synergistic and integrative approach. We will use a range of techniques including single cell electrophysiology, live-cell imaging, DREADD cellular manipulation and molecular biology to ultimately decipher physiological function. We will also use AAV expression and Cre-technology in transgenic rats that allows specific recording and manipulation in GABA neurons from the single cell to whole animal. Each technique directly complements the other, allowing an unparalleled depth of study. Together, these techniques allow the vertical study of the system and meticulous cellular investigation. Upon completion of the proposed research, we expect to identify the significance and mechanisms of elevated nTS activity due to reduced GABA signaling that result in cardiorespiratory abnormalities in IH diseases.