DEVELOPMENTAL CONTROL OF SYNAPSE STRUCTURE WITH LTP

描述(申请人提供)：树突棘是90%兴奋性突触的宿主；在许多扰乱中枢神经系统功能的发育障碍中，它们丢失或具有异常结构。总体目标是了解脊椎和突触结构在正常学习和记忆发展中的作用。长时程增强(LTP)是一种学习和记忆的突触模型，非常适合研究这一过程。脊椎被认为是重要的，因为它们隔离了核心结构和分子，这些结构和分子是依赖蛋白质合成的LTP(L-LTP)持续3小时所需的。清晰的理解需要从连续切片电子显微镜重建三维的纳米分辨率，这是本实验室首创的一种方法。我们提出了严格的实验来测试树突的形成和结构突触的可塑性是否为L-LTP在海马区的发育调控提供了一般机制，海马区是学习和记忆的关键大脑区域。目的1验证L-LTP在出生后12天突然发作与首次出现树突棘和结构突触可塑性有关的假说。这些实验将确定P12的树突、轴突、棘突和突触的结构和成分与P8和P10的区别，而P8和P10不是由一次TBS产生的。他们将测试在P12时产生的L-LTP是否像成熟的海马体那样平衡地消除小棘和扩大剩余的突触，以及突触前和突触后的结构重构在发育过程中是否与表达L-LTP的能力同步。目的2验证这样的假设，即TBS诱导树突棘，然后在P10第二轮TBS后用于维持L-LTP，而在P8不产生L-LTP的第二轮TBS后树突棘不起作用。目的3确定L-LTP在小鼠海马区的发育起始时间及其与超微结构的相关性，为今后利用遗传操作进行研究奠定基础。这些结果有望对学习和记忆的突触基础有新的见解，这是设计有效治疗发育性大脑疾病的必要知识。

DESCRIPTION (provided by applicant): Dendritic spines host >90 percent of excitatory synapses; they are lost or have abnormal structure in many developmental disorders that disrupt central nervous system function. The overall goal is to understand the role of spine and synapse structure in the normal development of learning and memory. Long-term potentiation (LTP) is a synaptic model of learning and memory well-suited to investigate this process. Spines are thought to be important because they sequester core structures and molecules needed for the protein synthesis-dependent or "late" phase of LTP (L-LTP) lasting >3hr. A clear understanding requires the nanometer resolution of 3D reconstruction from serial section electron microscopy, an approach pioneered in this laboratory. Rigorous experiments are proposed to test whether formation of dendritic spines and structural synaptic plasticity provide general mechanisms for the developmental regulation of L-LTP in hippocampus, a brain region crucial for learning and memory. Aim 1 is to test the hypothesis that the abrupt onset of L-LTP at postnatal day (P)12 is associated with first occurrence of dendritic spines and capacity for structural synaptic plasticity. The experiments will determine what differentiates dendritic, axonal, spine, and synaptic structure and composition at P12, from P8 and P10 when L-LTP is not produced by one bout of TBS. They will test whether production of L-LTP at P12 results in a balanced elimination of small spines and enlargement of remaining synapses as occurs in mature hippocampus and whether pre- and postsynaptic structural remodeling are synchronized during development with the ability to express L-LTP. Aim 2 is to test the hypothesis that dendritic spines are induced by TBS and then serve to sustain L-LTP after a second bout of TBS at P10, but not at P8, when multiple TBS do not produce L-LTP. Aim 3 is to ascertain the developmental onset of L-LTP and its ultrastructural correlates in mouse hippocampus as a foundation for future work using genetic manipulations. The outcomes promise new insight into the synaptic basis of learning and memory, essential knowledge to design effective treatments for developmental brain disorders.