Chemically specified synaptogenesis in the visual cortex

视觉皮层中化学指定的突触发生

• 批准号: 6795335
• 负责人: CHIYE J AOKI
• 金额: $ 26.36万
• 依托单位: NEW YORK UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-09-01 至 2007-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6795335
• 关键词: NMDA receptors; acetylcholine; action potentials; brain; chemical stimulation; cholinergic receptors; computer data analysis; early experience; electrodes; electron microscopy; electrophysiology; immunocytochemistry; laboratory rat; light microscopy; muscarinic receptor; neurons; newborn animals; organ culture; synaptogenesis; visual cortex; voltage /patch clamp

DESCRIPTION (adapted from applicant's abstract): The long-term goal is to understand the cellular and molecular mechanisms linking visual experience during early life to maturation of excitatory synapses in the visual cortex. The maturation of cortical synapses can be detected biophysically by a switch from EPSP depression following repetitive presynaptic action potentials (immature) to EPSP facilitation (more mature). The general working hypothesis is that the molecular composition of postsynaptic structures correlates with and confers the degree of maturity upon the presynaptic axons. We will test this hypothesis by combining patch-recording of multiple, synaptically connected neurons within neonatal rat visual cortical slices with electron microscopic (EM) - immuno- cytochemical (ICC) analysis of the recorded neurons to DETERMINE WHETHER: (1) the more mature, facilitating synapses exhibit the NMDA receptor (NMDAR) subunits - NR1, NR2A - at postsynaptic densities, as well as the muscarinic acetylcholinergic receptors (mAChR) pen-synaptically; (2) the immature, depressing synapses are characterized by pioneer NMDARs that arrive to the plasma membrane first, along with alpha7 nicotinic AChR; (3) activation of these 'pioneer' NMDARs regulate recruitment of cytoplasmic NMDAR subunits and mAChRs to nascent postsynaptic sites; (4) pharmacological blockade of NMDAR will prevent the insertion of NR1/NR2A heteromers of NMDAR and AChR and also delay or abolish the switch at synapses from the depressing to the facilitating phenotype. The works of Aoki and Reyes indicate that synapse maturity can vary widely within single layers and even within single neurons. Thus, the combined EM, ICC and biophysical analysis of single synapses and single postsynaptic densities should be particularly helpful in elucidating functional links between ultrastructure, molecular composition, and physiological properties of excitatory synapses that form during early postnatal life in the visual cortex and dictate life-long capacities of cortical neural function. The knowledge gained from such a study is required in designing molecular remedies for deficits caused by sensory deprivation during early life.

描述（改编自申请人的摘要）：长期目标是了解连接视觉体验的细胞和分子机制 从生命早期到视觉皮层兴奋性突触的成熟。 皮质突触的成熟可以通过开关进行生物物理检测 重复突触前动作电位后 EPSP 抑制 （不成熟）到 EPSP 促进（更成熟）。一般工作假设 突触后结构的分子组成与 并赋予突触前轴突成熟程度。我们将测试 这个假设通过结合多个突触的补丁记录 用电子连接新生大鼠视觉皮层切片内的神经元 对记录的神经元进行显微镜 (EM) - 免疫细胞化学 (ICC) 分析 确定是否：（1）更成熟、更容易的突触表现出 NMDA 受体 (NMDAR) 亚基 - NR1、NR2A - 也位于突触后密度 作为突触毒蕈碱乙酰胆碱能受体（mAChR）； （2） 不成熟、压抑的突触的特点是先锋 NMDAR 到达 首先与 α7 烟碱 AChR 一起到达质膜； (3)激活 这些“先锋”NMDAR 调节细胞质 NMDAR 亚基的募集 和 mAChR 至新生突触后位点； (4) NMDAR的药理阻断 将阻止 NMDAR 和 AChR 的 NR1/NR2A 异聚体的插入，并且 延迟或取消突触从抑制到促进的转换 表型。 Aoki 和 Reyes 的研究表明突触成熟度可能会有所不同 广泛存在于单层甚至单个神经元内。因此，合并后的 单突触和单突触后的 EM、ICC 和生物物理分析 密度对于阐明功能联系特别有帮助 超微结构、分子组成和生理特性之间的关系 出生后早期视觉皮层中形成的兴奋性突触 并决定皮质神经功能的终生能力。知识点 设计分子疗法时需要从此类研究中获得的信息 早年因感觉剥夺而导致的缺陷。