Consequences of Perinatal Nicotine Exposure on Functional Brainstem Development

项目总结 产前暴露在香烟烟雾中会增加婴儿猝死综合症的风险 持续到成年期的大脑发育缺陷。已经观察到感觉障碍，值得注意的是 在出生前接触香烟后，在听觉系统中。由于电子烟越来越受欢迎， 仅就产前尼古丁暴露进行研究的必要性就变得越来越重要。关键人物 小鼠的听觉发育期发生在出生后，允许围产期尼古丁准确地接触 模型产前尼古丁暴露对听觉系统表型的影响。在PNE模型中，被干扰的谷氨酸能 在听觉惊吓测试中，听觉皮质中的信号和时间处理受损已有报道。 然而，围产期尼古丁暴露(PNE)损害听觉发育的细胞机制 而中枢听觉处理目前尚不清楚。在听觉系统中，胆碱能信号是必需的。 用于外周和中枢听觉过程。最近的研究证明了尼古丁的重要性 大鼠斜角体内侧核(MNTB)中乙酰胆碱受体的信噪比检测 听觉脑干。谷氨酸能突触所必需的α7烟碱型乙酰胆碱受体(α7nAChR) 在海马区和皮质中的发育，在出生后早期的MNTB中高表达 发展。利用MNTB的大的谷氨酸能突触，拟议的研究旨在 研究PNE对MNTB突触的结构和功能发育的影响。 中枢听觉处理。中心假说是去甲肾上腺素增加α7nAChR的表达，并使其慢性 激活会损害MNTB内谷氨酸能突触的发育，导致中枢性听力障碍。由于 MNTB在双耳处理中的关键作用，研究PNE如何影响MNTB是很重要的 在听觉发育期间了解产前接触过的儿童的听觉加工障碍 尼古丁。目的1检测nAChRs在Calyx-MNTB突触的发育性表达及阿魏酸钠对其的影响 应用膜片钳电生理、免疫组织化学和免疫印迹等方法研究PNE对nAChR表达的影响。目标 2探讨去甲肾上腺素(PNE)对扣带突触体结构和功能的发育影响。直接 突触前记录的花盏末端将测量囊泡谷氨酸的释放，随后是3D 对花萼进行重建以量化结构发育。MNTB神经元的膜片钳记录 将进行传入纤维刺激以测量谷氨酸介导的电流，免疫组织化学将 在花冠突触中观察谷氨酸受体。Aim 3使用活体方法测试PNE后的听觉处理 听觉测试。提出的目标将揭示细胞和电路水平的机制 尼古丁暴露导致的听觉缺陷将对未来的治疗有用。

PROJECT SUMMARY Prenatal exposure to cigarette smoke increases the risk of sudden infant death syndrome as well as developmental deficits in the brain that persist into adulthood. Sensory impairments have been observed, notably in the auditory system, following prenatal cigarette exposure. Due to the increasing popularity of e-cigarettes, the need for research into prenatal exposure to nicotine alone is becoming increasingly important. The critical period of mouse auditory development occurs after birth, allowing for perinatal nicotine exposure to accurately model prenatal nicotine exposure on auditory system phenotypes. In PNE models, disrupted glutamatergic signaling in the auditory cortex and impaired temporal processing in an auditory startle test has been reported. However, the cellular mechanisms whereby perinatal nicotine exposure (PNE) impairs auditory development and central auditory processing are currently unknown. In the auditory system, cholinergic signaling is necessary for peripheral and central auditory processes. Recent work demonstrates the importance of nicotinic acetylcholine receptors in signal-in-noise detection in the medial nucleus of the trapezoid body (MNTB) of the auditory brainstem. The alpha 7 nicotinic acetylcholine receptor (α7 nAChR), essential for glutamatergic synapse development in the hippocampus and cortex, is highly expressed in the MNTB during early postnatal development. Utilizing the large glutamatergic Calyx of Held synapse of the MNTB, the proposed studies aim to investigate the effect of PNE on structural and functional development of the calyx terminal, MNTB synapse, and central auditory processing. The central hypothesis is that PNE increases α7 nAChR expression and its chronic activation impairs glutamatergic synapse development in the MNTB resulting in central auditory deficits. Due to the crucial role of MNTB in binaural processing, it is important to examine how the MNTB is affected by PNE during auditory development to understand auditory processing disorders in children prenatally exposed to nicotine. Aim 1 examines developmental expression of nAChRs at the calyx-MNTB synapse and the effect of PNE on nAChR expression using patch-clamp electrophysiology, immunohistochemistry, and western blot. Aim 2 investigates the developmental impact of PNE on the structure and function of calyx of Held synapse. Direct presynaptic recordings of the calyx terminal will measure vesicular glutamate release followed by 3D reconstruction of the calyx to quantify structural development. Patch clamp recordings of the MNTB neuron with afferent fiber stimulation will be done to measure glutamate-mediated currents, and immunohistochemistry will visualize glutamate receptors in the calyx synapse. Aim 3 tests auditory processing following PNE using in vivo auditory tests. The proposed aims will reveal cellular and circuit-level mechanisms underlying developmental nicotine exposure-induced auditory deficits that will be useful for future therapeutics.