Determining the mechanisms underlying a potential treatment for sleep apnea

描述（由申请人提供）：在新生大鼠髓片制备过程中，发现了一种深刻而持久的内源性呼吸相关舌下神经活动促进。这是AMPA受体抗脱敏药物环噻嗪（CTZ） 1小时浴敷的结果。这种现象被称为CTZ诱导的促化（CIF），在给药完成后持续100 - 12小时，但不依赖于CTZ给药期间嗜离子性谷氨酸受体的激活。这种舌下神经活动的促进作用是本实验室研究的另一种呼吸可塑性模型体外长期促进作用（ivLTF）的三倍。重要的是，这些观察结果与行为相关。在异氟醚麻醉的成年大鼠体内注射CTZ可促进相性颏舌肌（GG）肌活动幅度，但不影响呼吸频率和心率。CIF的发病机制尚不清楚。该项目将测试3种机制，基于初步数据，在更详细地描述这一现象的动力学和细胞内效应之后，这些机制很可能是CIF的基础。目标1有两个目标：(i)确定CTZ应用的持续时间以及CTZ浓度是否决定了CIF的大小和时间进程；（ii）通过将CTZ局部应用于已知影响呼吸节律的切片中的3个区域，分析CTZ对呼吸控制电路的影响。目的2研究CTZ暴露如何在短期和长期内改变舌下运动神经元内的快速兴奋性信号、抑制性信号和放电特性，为测试CIF的假设机制建立基线细胞内反应。目标3测试了假设为CIF基础的机制：(i)永久消除AMPA受体脱敏，（ii）直接细胞内作用，（iii）破坏构成型AMPA受体再循环。相关性：阻塞性睡眠呼吸暂停（OSA）是一种影响多达五分之一美国成年人的疾病，其严重程度不同。目前，没有药物治疗这种疾病；然而，其他治疗方法具有高度侵入性和/或效果有限。对呼吸运动输出到舌头和上呼吸道肌肉的机制的理解将促进有效、易于使用的治疗方法的发展，改善数百万人的长期健康。

DESCRIPTION (provided by applicant): A profound and long-lasting facilitation of endogenously-generated, respiratory- related hypoglossal nerve activity in the neonatal rat medullary slice preparation has been discovered. It results from a 1-hour bath application of the AMPA receptor anti-desensitization drug cyclothiazide (CTZ). This phenomenon, termed CTZ-induced facilitation (CIF), consistently lasts >12 hours following the completion of drug application but does not depend upon activation of ionotropic glutamate receptors during administration of CTZ. This facilitation of hypoglossal nerve activity is triple that seen in another model of respiratory plasticity studied in this lab, in vitro long-term facilitation (ivLTF). Importantly, these observations are behaviorally relevant. Injection of CTZ into intact, isoflurane-anesthetized, adult rats facilitates the amplitude of phasic genioglossus (GG) muscle activity without affecting respiratory rate or heart rate. The mechanism underlying CIF is unknown. This project will test 3 mechanisms that, based on preliminary data, most likely underlie CIF, after characterizing the dynamics and intracellular effects of this phenomenon in greater detail. Aim 1 has two objectives: (i) determine whether the duration of CTZ application along with CTZ concentration determines the magnitude and time course of CIF; (ii) parse the effects of CTZ on the respiratory control circuit by focally applying CTZ to 3 regions in the slice known to affect respiratory rhythm. Aim 2 investigates how CTZ exposure modifies fast excitatory signaling, inhibitory signaling, and firing properties within hypoglossal motoneurons in the short and long terms, establishing a baseline intracellular response for testing the mechanisms hypothesized to underlie CIF. Aim 3 tests the mechanisms hypothesized to underlie CIF: (i) permanent abolition of AMPA receptor desensitization, (ii) direct intracellular action, (iii) disruption of constitutive AMPA receptor recycling. RELEVANCE: Obstructive sleep apnea (OSA) is a disease that affects as many as 1 in 5 adult Americans in varying degrees of severity. Currently, there is no pharmacological treatment for this disease; while, other methods of treatment are highly invasive and/or of limited effectiveness. An understanding of the mechanisms underlying facilitation of respiratory motor output to muscles of the tongue and upper airway will foster the development of effective, easy to use treatments improving the long-term health of millions.