Thyroid hormones and synaptic function

虽然甲状腺激素(TH)在神经系统发育过程中是严格需要的，但其作用的分子基础却知之甚少。该项目的长期目标是阐明胚胎组织中THs调节突触功能的分子机制。蝌蚪尾部的神经肌肉接头(NMJ)是研究神经调节的一个很好的系统，因为它在TH存在的情况下通过细胞凋亡而死亡。具体目的1.确定胆碱能受体和神经末梢在发育的几个阶段的分布，表征这个突触系统的解剖特征是了解TH的非基因组作用的第一步。我们将检验这一假设，即负责突触传递的AChRs优先/y位于肌纤维的末端。具体目的2.确定TH在突触前对突触小泡再循环的急性作用及其与细胞内钙水平的关系。我们将检验这样的假设，即观察到的增强的MEPC频率 作为对T3结果的响应，这些结果来自增强囊泡回收。将考虑两个独立的子目标：(A)确定TH在调节囊泡循环中的作用，以及(B)评估细胞内钙水平在调节TH的作用中的作用。具体目的3.评价甲状腺激素对AChR的急性突触后作用。我们将验证这一假设，即TH直接与突触后AC受体相互作用，第二，被T3改变的AChR的钙动员导致AChR动力学活动的改变。 这些实验将包括三项强大的技术：近红外(NIR)显微镜、激光扫描共聚焦显微镜(LSCM)和传统电生理学。高亲和力和低亲和力的钙染料将用于评估突触前和突触后区域的钙水平。这项研究将提供与临床应用相关的信息，包括联合使用和/或使用T3的治疗。重要的是，神经细胞的凋亡 现在被认为在许多中枢神经系统退行性疾病(例如帕金森氏病和阿尔茨海默病)以及外周(例如各种神经疾病和视网膜退化)的病理中发挥着重要作用。细胞凋亡在这些不同的生理和病理过程中的关键作用表明，细胞凋亡的药理学及其作用将成为生物技术和临床应用的重要靶点。

Although thyroid hormones (THs) are strictly required during developing nervous system, the molecular bases of their action are poorly understood. The long-term goal of this project is to elucidate the molecular mechanism by which synaptic function is modulated by THs in embryonic tissue. The Neuromuscular junction (NMJ) of tadpole tail is an excellent system to study neuromodulation, because it dies by apoptosis in the presence of THs. Specific Aim 1. Determine the distribution of cholinergic receptors and nerve terminals tadpole tails at several stages of development, The Characterization of the anatomical features of this synaptic system represents the first step towards understanding the non-genomic actions of THs. We will test the hypothesis that the AChRs responsible for synaptic transmission are preferential/y located within the extreme rostral of the muscular fiber. Specific Aim 2. Determine the acute pre-synaptic action of THs on synaptic vesicle recycling and its relationship to intracellular calcium level. We will test the hypothesis that the enhanced mepc frequency observed in response to T3 results from augmented vesicle recycling. Two separated sub-aims will be considered: (a) to determine the role of THs in modulating vesicle recycling, and (b) to assess the role of intracellu/ar calcium level in mediating the actions of TH. Specific Aim 3. Assess the acute postsynaptic action of thyroid hormones on the AChR. We will test the hypothesis that THs interact directly with the postsynaptic AC-receptor and secondly that the calcium mobilization by the AChR that is alter by T3 causes chanties in the AChR kinetic activity. The experiments will include three powerful techniques: Near Infrared (NIR) microscopy, Laser Scanning Confocal Microscopy (LSCM) and conventional electrophysiology. High and low affinity calcium dyes will be used to evaluate calcium levels in the pre- and post-synaptic regions. This study will provide information that is relevant to clinical applications including treatments in which T3 is being co-administrated and/or used. Importantly, neuronal apoptosis is now thought to play a significant role in the pathology of a number of degenerative diseases of the CNS (e.g. Parkinson's and Alzheimer's diseases) as well as in the periphery (for example, various neuropathies and retinal degeneration). The key role of apoptosis in these diverse physiological and pathological processes suggests that the pharmacology of apoptosis and the actions of THs will become important targets for biotechnology and for clinical applications.