SYNAPTIC TRANSMISSION DURING NEURONAL DIFFERENTIATION

描述（由申请人提供）：中枢前庭系统在外周前庭损伤后表现出许多功能的显著自然恢复。参与这种可塑性的第一个大脑中心是前庭核，它们的完整性对恢复至关重要。这项工作的主要目标是了解如何兴奋性和突触传递的变化，在一类确定的前庭核神经元在补偿从单侧前庭神经节切除术的。将在幼雏和整个动物的脑切片中研究小鸡的切向核（前庭外侧核）。其主细胞参与两个前庭反射的损害，但显示恢复。我们建议，在突触和内在的膜特性和/或树突状终端的变化可能会发生在前庭核在补偿。这些技术包括脑切片膜片钳记录、药理学测试和免疫标记结合共聚焦成像。将在幼雏（出生后4-5天）中制造损伤，在补偿期间的选定阶段（手术后6、12、24小时; 3和7天）处死幼雏。到H4-5，这些神经元建立了成熟的放电模式，包括自发放电和诱发重复放电。具体的目的包括：用全细胞膜片钳技术记录同侧和对侧切向主细胞的自发放电、自发突触活动和电压门控外向钾电流，研究前庭诱发的对侧切向主细胞的放电和突触电流，以及AMPA受体亚单位的免疫细胞化学研究（GluR 1，GluR 2，GluR 2/3，GluR 4），钾离子通道（Kv1.1，Kv1.2）和间隙连接通道（连接蛋白）。研究范围将扩大取样其他前庭神经元可能有助于补偿，包括延长细胞的切向核和细胞类型B的内侧前庭核。对于第一次，信号处理将研究使用最先进的方法在一个同质的，形态学上确定的前庭核神经元组在选定的时间从单侧前庭神经节切除术的行为恢复。随着控制前庭核神经元兴奋性和突触传递的基本机制被更好地理解和分子靶点的确定，将设计出更有效的治疗方法来治疗由疾病、损伤和衰老引起的中枢前庭疾病。

DESCRIPTION (provided by applicant): The central vestibular system exhibits a remarkable natural recovery of many functions after peripheral vestibular lesions. The first brain centers involved in this plasticity are the vestibular nuclei, and their integrity is crucial for recovery. The major goal of this work is to understand how excitability and synaptic transmission change in an identified class of vestibular nucleus neurons during compensation from unilateral vestibular ganglionectomy's. The chick tangential nucleus (lateral vestibular nucleus) will be studied in brain slices of hatchling chicks and in whole animals. Its principal cells participate in two vestibular reflexes affected by the lesion, but show recovery. We propose that changes in synaptic and intrinsic membrane properties and/or dendritic terminals may occur in vestibular nuclei during compensation. The techniques include patch-clamp recording in brain slices, pharmacological testing, and immunolabeling combined with confocal imaging. Lesion will be made in hatchling chicks (4-5 days postnatal) that are sacrificed at selected stages during compensation (6, 12, 24 hours; 3 and 7 days after surgery). By H4-5, the mature firing pattern, including spontaneous spike firing and evoked repetitive firing, is established in these neurons. The specific aims include whole-cell patch-clamp recordings of spontaneous spike firing, spontaneous synaptic activity, and voltage-gated outward potassium currents in the ipsi- and contra lateral tangential principal cells, studies on vestibular-evoked spike firing and synaptic currents in the contra lateral tangential principal cells, and immunocytochemical studies of AMPA receptor subunits (GluR1, GluR2, GluR2/3, GluR4), potassium (Kv1.1, Kv1.2) and gap junction channels (connexins) in the ipsi- and contra lateral tangential nucleus. The scope of the study will be broadened by sampling other vestibular neurons likely to contribute to compensation, including elongate cells of the tangential nucleus and cell type B of the medial vestibular nucleus. For the first time, signal processing will be studied using state-of-art methods in a homogeneous, morphologically identified group of vestibular nucleus neurons at selected times during behavioral recovery from unilateral vestibular ganglionectomy's. As the basic mechanisms controlling excitability and synaptic transmission in vestibular nucleus neurons are better understood and molecular targets are identified, more effective therapies will be devised to treat central vestibular disorders resulting from disease, injury and aging.