Interdependence among neuromodulators of ventilatory control

描述（由申请人提供）：呼吸网络内的神经元启动并协调呼吸泵和气道肌肉的激活，以调节肺通气(I)水平，维持血气稳态。化学感受器为呼吸提供主要的兴奋性驱动（19,22,31,35,65,82），但最终决定呼吸网络兴奋性的是兴奋性和抑制性神经调节剂的总体平衡（15,16,28,92）。内源性神经调节剂在清醒或睡眠时对兴奋I的贡献尚未确定，但体外证据表明“调节剂的作用是由与其他神经调节剂的并发调节和相互作用决定的”（16）。我们建议的总体目标是验证神经调节相互依赖的假设，并测试相互依赖不足是否会导致睡眠呼吸障碍（SDB）和/或阿片类药物过量诱导的呼吸抑制。在成年山羊中，在清醒和睡眠状态下，微管将被长期植入到preB¿tzinger复合物（preB¿tC）或舌下运动核（HMN）探针中，用于在模拟脑脊液（mCSF）中透析兴奋性或抑制性神经调节剂的拮抗剂或激动剂。我们将测量I，膈肌和颏舌肌（GG）的肌肉活动，以及流出物透析mCSF中的神经化学物质。特异性目的1确定preB¿tC内多种兴奋性神经调节剂之间是否存在相互依赖关系。我们假设：a)毒碱胆碱能、5-羟色胺（5-HT2A）或神经激肽-1受体的拮抗剂单独对I和GG肌肉活动影响很小或没有影响，但联合使用会减弱I和GG活动，特别是在睡眠期间，并导致SDB； b)兴奋性神经调节输入到前b¿tC的拮抗剂会在拮抗剂透析部位产生其他神经调节剂的代偿性变化。特异性目的2确定在preB - tC内兴奋性神经调节剂与阿片受体激活的抑制性神经调节作用之间是否存在相互依赖关系。我们假设：a) preB¿tC¿-阿片受体激活会在清醒时和睡眠时更大程度地抑制I和GG活性；b) preB¿tC¿-阿片受体激活不会改变流出物的神经化学物质含量；c) -阿片受体激活诱导的I和GG活性下降将通过-阿片受体激动剂和5-HT1A或5-HT4A受体激动剂的共透析而减弱。特异性Aim 3确定HMN的神经调节剂之间是否存在相互依赖关系。我们假设:害怕)单边透析-阿片受体激动剂在非快速眼动睡眠期间卫生计量系统网络将减少我和GG活动和REM睡眠将导致深发展,b)将没有补偿任何变化测量当地的化学物质的废水mCSF阿片类药物透析期间,和c)他们的阿片受体activation-induced减少我和GG活动会害怕co-dialysis减毒的阿片受体激动剂、5-HT1A受体激动剂或5-HT4A受体。

DESCRIPTION (provided by applicant): Neurons within the respiratory network initiate and coordinate respiratory pump and airway muscle activation to adjust the level of pulmonary ventilation ( I) to maintain blood gas homeostasis. Chemoreceptors provide major excitatory drives to breathe (19, 22, 31, 65, 82), but it is the overall balance of excitatory and inhibitory neuromodulators that ultimately determine respiratory network excitability (15, 16, 28, 92). The contribution of endogenous neuromodulators to eupneic I while awake or asleep has not been determined, but in vitro evidence suggests "that a modulator's action is determined by the concurrent modulation and interaction with other neuromodulators" (16). The overall goal of our proposal is to test this hypothesis of neuromodulatory interdependence and test whether inadequate interdependence contributes to sleep disordered breathing (SDB) and/or opiate overdose-induced respiratory depression. In adult goats, microtubules will be chronically implanted for insertion into the preB¿tzinger Complex (preB¿tC) or hypoglossal motor nucleus (HMN) of probes for dialysis in mock cerebral spinal fluid (mCSF) of antagonists or agonist of excitatory or inhibitory neuromodulators during awake and asleep states. We will measure I, diaphragm and genioglossus (GG) muscle activity, and neurochemicals in effluent dialyzed mCSF. Specific Aim 1 determines whether there is interdependence among multiple excitatory neuromodulators within the preB¿tC. We hypothesize that: a) antagonists of muscarinic cholinergic, serotonin (5-HT2A), or neurokinin-1 receptors individually will have little or no effet on eupneic I and GG muscle activity but in combination will attenuate I and GG activity particularly during sleep and lead to SDB, b) antagonists of excitatory neuromodulatory inputs to the preB¿tC will produce compensatory changes in other neuromodulators at the site of antagonist dialysis. Specific Aim 2 determines whether there is interdependence within the preB¿tC between excitatory neuromodulators and the inhibitory neuromodulatory effects of ¿-opioid receptor activation. We hypothesize that: a) preB¿tC ¿-opioid receptor activation will depress I and GG activity while awake and to a greater extent during sleep, b) preB¿tC ¿-opioid receptor activation will not alter effluent neurochemical content and c) the ¿-opioid receptor activation-induced decreased I and GG activity will be attenuated by co-dialysis of the ¿-opioid agonist and agonists of 5-HT1A, or 5-HT4A receptors. Specific Aim 3 determines whether there is interdependence among neuromodulators of the HMN. We hypothesize that: a) unilateral dialysis of a ¿- opioid agonist within the HMN will decrease I and GG activity which during NREM and REM sleep will lead to SDB, b) there will be no compensatory changes in any of the measured local neurochemicals in the effluent mCSF during opioid dialysis, and c) the ¿-opioid receptor activation-induced decreased I and GG activity will be attenuated by co-dialysis of the ¿-opioid agonist and agonists of 5-HT1A, or 5-HT4A receptors.