Homeostatic Effects of Activity on Neurotransmission

描述(由申请人提供)： 电兴奋性的慢性变化深刻地影响着神经元整个生命周期中的突触传递。依赖活动的可塑性可表现为对随后的突触信号的上调或下调，并可通过突触前和突触后靶点发生。这项应用的目的是使用复杂的成像技术来检查海马神经元对强直去极化模拟的电活动增加的反应。其基本原理是，如果我们能够理解紧张性去极化伴随的神经元信号变化，那么我们就应该深入了解药物滥用以及神经元损伤和疾病引发的动态平衡机制。在初步的膜片钳电生理学研究中，紧张性去极化引起随后谷氨酸神经传递的稳态下降。在这项拟议的研究中，假设突触前突触小泡池的改变可以解释这种下降。选择性地抑制兴奋性神经元释放的谷氨酸可能是突触对滥用药物反应的一个模型，其中许多药物的作用是通过长时间改变总体活动水平来实现的。为了全面描述谷氨酸信号转导的缺陷，提出了免疫组织化学、电子显微镜和生命荧光染料(FM1-43)实验来补充先前的电生理学数据。成像和电生理方法的结合也将被用来确定紧张性去极化后谷氨酸传递受阻的分子机制。这些先进成像技术的培训将极大地促进申请者的职业发展，使她能够从多个角度评估突触功能。重要的是，在这些研究过程中获得的科学和技术专业知识将使候选人能够实现她在神经科学领域建立独立研究生涯的长期目标。

DESCRIPTION (provided by applicant): Chronic changes in electrical excitability profoundly affect synaptic transmission throughout the lifetime of a neuron. Activity-dependent plasticity can be manifest as the up- or down regulation of subsequent synaptic signaling, and can occur through both presynaptic and postsynaptic targets. The objective of this application is to use sophisticated imaging techniques to examine the neuronal response to increased electrical activity, as mimicked by tonic depolarization, in hippocampal neurons. The rationale is that if we can understand the signaling changes in neurons that accompany tonic depolarization, then we should gain insight into the homeostatic mechanisms that are initiated by drugs of abuse, as well as by neuronal injury and disease. In preliminary patch-clamp electrophysiology studies, tonic depolarization elicited a homeostatic decrease in subsequent glutamate neurotransmission. In the proposed study, it is hypothesized that a presynaptic alteration of the synapic vesicle pool accounts for this decrease. A selective, homeostatic depression of glutamate release from excitatory neurons may be a model for the response of synapses to drugs of abuse, many of which act by altering overall activity levels for prolonged periods. In order to characterize the deficits in glutamate signaling fully, immunohistochemistry, electron microscopy, and vital fluorescent dye (FM1-43) experiments are proposed to supplement the previous electrophysiology data. The combination of imaging and electrophysiological methods will also be used to define the molecular mechanisms responsible for the depression of glutamate transmission after tonic depolarization. Training in these advanced imaging techniques will greatly enhance the career development of the applicant, allowing her to assess synaptic function from many perspectives. Importantly, the scientific and technical expertise gained in the course of these studies will allow the candidate to attain her long-term goal of establishing an independent research career in neuroscience.