SYNAPTIC TRANSMISSION DURING NEURONAL DIFFERENTIATION

描述(申请人提供)：外周前庭病变后，中央前庭系统表现出显著的许多功能的自然恢复。参与这种可塑性的第一个大脑中心是前庭核团，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的代偿过程中，一类已识别的前庭核神经元的兴奋性和突触传递的变化。鸡的切线核(前庭外侧核)将在雏鸡和整个动物的脑片上进行研究。它的主要细胞参与受损伤影响的两个前庭反射，但显示出恢复。我们认为在代偿过程中，前庭核团的突触和固有膜特性和/或树突终末可能发生改变。这些技术包括脑片膜片钳记录、药理学测试以及结合共聚焦成像的免疫标记。在代偿期间的特定阶段(6、12、24小时；手术后3天和7天)处死幼鸡(出生后4-5天)，造成损伤。通过H4-5，在这些神经元中建立了成熟的放电模式，包括自发的棘波放电和诱发的重复放电。具体目标包括全细胞膜片钳记录IPSI和对侧切向主细胞的自发放电、突触活动和电压门控外向钾电流，研究对侧切向主细胞的前庭诱发的放电和突触电流，以及对IPSI和对侧切向核中AMPA受体亚单位(GluR1、GluR2、GluR2/3、GluR4)、钾(Kv1.1、Kv1.2)和缝隙连接通道(Connecexins)的免疫细胞化学研究。研究范围将通过采样其他可能有助于代偿的前庭神经元来扩大，包括切向核的细长细胞和前庭内侧核的B型细胞。在单侧前庭神经节切除后的行为恢复过程中，将首次使用最先进的方法在选定的时间对一组均匀的、形态识别的前庭核神经元进行信号处理研究。随着对前庭核神经元兴奋性和突触传递的基本机制的更好理解和分子靶点的确定，将设计出更有效的治疗由疾病、损伤和衰老引起的中枢性前庭疾病的方法。

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.