Presynaptic Direct Structure-Function Analysis

突触前直接结构功能分析

• 批准号: 0131459
• 负责人: Robin Cooper
• 金额: $ 23.23万
• 依托单位: University of Kentucky Research Foundation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-08-15 至 2006-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0131459&HistoricalAwards=false
• 关键词: Presynaptic; Direct; Structure; Function; Analysis

The accepted model for chemical transmission at the neuromuscular junction is that when an action potential reaches the nerve terminal, voltage-sensitive calcium channels open which leads to a cascade of events resulting in vesicles fusing with the presynaptic membrane to release their contents into the synaptic cleft. The number of active zones within synapses, and not necessarily the size or numbers of synapses per se, is correlated to the degree of synaptic efficacy. Additional factors besides structural elements have a role in synaptic efficacy, but the purpose of this study is to focus on structural correlations. Investigating the function of individual synapses is essential to understanding the mechanisms that influence the efficacy of chemical synaptic transmission. The known simplicity of the synaptic structure at the crayfish opener neuromuscular junction and its quantal nature of release allow an assessment of discrete synapses within the motor nerve terminals. By analyzing areas of a quantal current trace using modern statistical techniques, it is noted that the gold standard= of directly counting quantal events is unstable in determining the number of release sites (n) and the probability of release at these sites (p) when the probability of release is low. This classical approach estimates one site even when there are clearly multiple sites operating. Modern methods used in this investigation estimate the probability of release at each site (p) to determine whether new sites are recruited as the firing frequency is increased. The proposed investigations directly correlate quantal parameters by various statistical methods to synaptic structure. An established method of identifying and recording from a synaptic site allows for its subsequent serial reconstruction using electron microscopic techniques. Thus, the same region can be serial sectioned and reconstructed from electron micrographs to directly correlate function to synaptic ultra structure. This effort will provide a clearer understanding of the mechanisms employed by structural elements that influence synaptic efficacy and mechanisms underlying frequency facilitation of transmitter release in crustaceans.

神经肌肉接头化学传递的公认模型是，当动作电位到达神经末梢时，电压敏感的钙通道打开，导致一系列事件，导致囊泡与突触前膜融合，将其内容物释放到突触间隙。 突触内活动区域的数量（不一定是突触本身的大小或数量）与突触功效的程度相关。除了结构元素之外，其他因素也在突触功效中发挥作用，但本研究的目的是关注结构相关性。研究单个突触的功能对于理解影响化学突触传递功效的机制至关重要。小龙虾开启器神经肌肉接头突触结构的已知简单性及其释放的量子性质允许评估运动神经末梢内的离散突触。通过使用现代统计技术分析量子电流迹线的区域，我们注意到，当释放概率较低时，直接计数量子事件的黄金标准在确定释放位点的数量 (n) 和这些位点的释放概率 (p) 方面是不稳定的。即使明显有多个站点在运行，这种经典方法也会估计一个站点。本次调查中使用的现代方法估计每个站点的释放概率 (p)，以确定随着发射频率的增加是否会招募新的站点。所提出的研究通过各种统计方法将量子参数直接与突触结构相关联。一种从突触位点识别和记录的既定方法允许使用电子显微镜技术对其进行后续的连续重建。因此，可以从电子显微照片对同一区域进行连续切片和重建，以直接将功能与突触超结构相关联。这项工作将使人们更清楚地了解影响甲壳类动物突触功效的结构元件所采用的机制以及促进递质释放的频率的机制。