DENDRITIC SPINES, SYNAPSES, AND LONG TERM POTENTIATION

树突棘、突触和长期增强

• 批准号: 2264097
• 负责人: KRISTEN M HARRIS
• 金额: $ 17.88万
• 依托单位: BOSTON CHILDREN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 1984
• 资助国家: 美国
• 起止时间: 1984-07-01 至 1995-09-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2264097
• 关键词: aminoacid analog; aminophosphonate; dendrites; developmental neurobiology; electron microscopy; hippocampus; laboratory rat; learning; long term potentiation; memory; mental retardation; neural plasticity; neuroanatomy; neurophysiology; neuropil; synapses; synaptic vesicles; synaptogenesis; tissue /cell preparation

More than 90% of the excitatory synapses in the central nervous system occur on dendritic spines. Changes in the structure of these tiny protrusions have long been implicated in learning and memory, though a clear delineation of such morphological changes has awaited the magnification and resolution provided by serial electron microscopy (EM). Long term potentiation (LTP) is an enduring change in synaptic efficacy that is widely studied as a cellular memory mechanism. Numerous anatomical studies have searched for anatomical correlates of LTP. These studies have lacked sufficient resolution to determine accurately the magnitude of the reported changes in the number of morphology of synapses and dendritic spines. A complete morphometric study is proposed to delineate the anatomical alterations at synapses and dendritic spines, to define their duration, and to relate these to various stages of LTP. The specific aims are: 1) To delineate the changes in synaptic and dendritic spine morphology that are associated with early and late phases of LTP in the hippocampus of postnatal day 15 (P15). This age is chosen because LTP is robust and enduring, even though the spines, synapses and dendrites have not attained their mature numbers or morphology. Because vigorous synaptogenesis is occurring at this age, multiple candidates exist for morphological plasticity that could subserve LTP. 2) To test whether mature synapses express morphological correlates of LTP that are similar to or different from those delineated at P15. It is essential for the understanding of mature memory mechanisms to establish whether mature synapses are similar to, differ only in degree from, or are categorically different from P15 synapses in their morphological plasticity. Methods: Standard procedures will be used to maintain in vitro hippocampal slices and induce and measure LTP extracellularly. Control hippocampal slices will receive the same stimulation paradigms as the LTP slices, But in the presence of DL-2-amino-phosphono-valeric acid (APV), a known blocker of LTP. Rapid microwave-enhanced fixation and routine processing will be used to prepare slices for electron microscopy. The irregularity in shape of dendritic spines and their synapses makes it impossible to extrapolate from partial measurements to their complete dimensions. Thus, the technically demanding approach of three-dimensional reconstruction from serial EM is required. Historically, the main drawback of serial EM has been the small sample sizes utilized because of the labor-intensive nature of the work. A new unbiased approach for sampling large areas of neutrophil in combination with serial EM is proposed to obtain accurate characterization of synaptic, spine, and dendritic morphologies and to allow for complete quantification of their ultrastructure in three dimensions. Health Relatedness: Improved understanding about the cell biology of learning and memory will help to clarify the cellular mechanisms underlying mental retardation or cognitive deterioration that occurs with many disorders of the central nervous system.

中枢神经系统中超过90％的兴奋性突触 发生在树突状的棘突上。这些微小的结构的变化 长期以来，突出与学习和记忆有关，尽管 明确描述了这种形态学变化已等待 串行电子显微镜提供的放大和分辨率 （em）。长期增强（LTP）是突触的持久变化 广泛研究为细胞记忆机制的功效。很多的 解剖学研究已搜索LTP的解剖学相关性。这些 研究缺乏足够的分辨率来准确确定 报告的形态数量变化的大小 突触和树突状刺。提出了一项完整的形态计量研究 描绘突触和树突状的解剖学变化 刺，定义其持续时间，并将其与各个阶段联系起来 LTP的 具体目的是：1）描述突触的变化和 与早期和晚期相关的树突状脊柱形态 LTP的阶段在产后第15天的海马（P15）。这个年龄是 之所以选择，是因为LTP强大而持久，即使刺， 突触和树突没有达到其成熟数字或 形态学。因为在这个年龄发生剧烈的突触发生，所以 存在多个候选者，以实现形态可塑性 维持LTP。 2）测试成熟的突触是否表达形态学 LTP的相关性与所划定的相似或不同 在P15。这对于理解成熟记忆至关重要 确定成熟突触是否相似的机制不同 仅在程度上，或与p15突触有明确不同 它们的形态可塑性。 方法：标准程序将用于维持体外 海马切片，并诱导并测量LTP细胞外。控制 海马切片将获得与 LTP切片，但在存在DL-2-氨基 - 磷酸谷酸的情况下 （APV），LTP的已知阻滞剂。快速微波增强的固定和 常规处理将用于准备电子切片 显微镜。树突状刺及其形状的不规则性 突触使得不可能从部分测量到 他们的完整尺寸。因此，技术要求的方法 需要从串行EM进行三维重建。 从历史上看，串行EM的主要缺点是很小的样本 由于工作的劳动密集型性质而被使用。一个新 无偏见的方法，用于合并中性粒细胞的大面积 提出了串行EM以获得准确的表征 突触，脊柱和树突形态，并允许完整 在三维中对其超微结构进行定量。 健康相关性：提高对细胞生物学的了解 学习和记忆将有助于阐明细胞机制 发生的潜在智力降低或认知恶化 中枢神经系统的许多疾病。