SYNAPTIC TRANSMISSION DURING NEURONAL DIFFERENTIATION

描述（由申请人提供）：周围前庭病变后，中央前庭系统显示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。这项工作的主要目的是了解在单侧前庭神经节切除术的代偿过程中，一类已确定的前庭核神经元的兴奋性和突触传递是如何变化的。将在幼雏和全动物的脑切片上研究小鸡切向核（外侧前庭核）。其主要细胞参与受病变影响的两种前庭反射，但显示恢复。我们提出突触和固有膜特性和/或树突末梢的变化可能发生在前庭核代偿期间。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。雏鸡（出生后4-5天）在补偿的特定阶段（术后6、12、24小时；术后3、7天）被处死。通过H4-5，在这些神经元中建立了成熟的放电模式，包括自发的spike放电和诱发的重复放电。具体目标包括全细胞膜片钳记录自发的尖峰放电、自发的突触活动和电压门控向外钾电流在单侧和对侧切向主细胞中，前庭诱发的尖峰放电和对侧切向主细胞中的突触电流的研究，以及AMPA受体亚基（GluR1、GluR2、GluR2/3、GluR4）、钾（Kv1.1、Kv1.1和Kv1.1）的免疫细胞化学研究。Kv1.2)和对侧切向核的间隙连接通道（连接蛋白）。研究的范围将通过采样其他可能参与代偿的前庭神经元来扩大，包括切向核的细长细胞和内侧前庭核的B型细胞。在单侧前庭神经节切除术后的行为恢复过程中，信号处理将首次使用最先进的方法在一个均匀的、形态学上确定的前庭核神经元组中进行研究。随着对前庭核神经元兴奋性和突触传递控制的基本机制的进一步了解和分子靶点的确定，将设计出更有效的治疗方法来治疗疾病、损伤和衰老引起的前庭中枢疾病。

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.