SYNAPTOGENESIS IN THE CEREBRAL CORTEX

描述(逐字摘自申请者摘要)：长期目标是 了解连接感觉体验的细胞和分子机制 从生命早期到躯体感觉兴奋性突触的成熟 大脑皮层。皮质突触的成熟可以通过生物物理学检测到 重复突触前动作电位后的EPSP抑制转换 (不成熟)到EPSP易化(更成熟)。一般工作假说 突触后结构的分子组成与 并赋予突触前轴突成熟的程度。我们将测试 这一假说是通过结合多个突触的斑块记录 大鼠体感觉皮层脑片内的电子连接神经元 对记录的神经元进行显微(EM)-免疫细胞化学(ICC)分析 确定：(1)更成熟、更容易的突触是否表现出NMDA 受体(NMDAR)亚单位-NR1、NR2a以及AMPA受体和神经元 突触后密度的一氧化氮合酶(NNOS)； 令人沮丧的突触的特征是到达 质膜首先通过PSD-95激活神经元型一氧化氮合酶； 这些先驱NMDAR调节细胞质NMDAR和AMPA的招募 受体亚基与新生突触后部位的关系；(4)药物阻断 将阻止NMDAR和AMPA的NR1/NR2A异构体的插入 受体，也延迟或取消突触的开关从压抑 与促进表型有关。青木和雷耶斯的作品表明 突触成熟度在单层内甚至在单层内可能有很大差异 神经元。因此，EM、ICC和生物物理联合分析单个突触 而单个突触后密度尤其有助于阐明 超微结构、分子组成和 早期形成的兴奋性突触的生理特性 躯体感觉皮层的出生后生活和决定人的终生能力 皮质神经功能。从这样的研究中获得的知识需要在 设计治疗感觉剥夺所致缺陷的分子疗法 早年的生活。

DESCRIPTION(Verbatim from the Applicant's Abstract): The long-term goal is to understand the cellular and molecular mechanisms linking sensory experience during early life to maturation of excitatory synapses in the somatosensory 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 rat somatosensory 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, as well as the AMPA receptors and neuronal nitric oxide synthase (nNOS) at postsynaptic densities; (2) the immature, depressing synapses are characterized by 'pioneer' NMDARs that arrive to the plasma membrane first, along with neuronal nNOS via PSD-95; (3) activation of these pioneer NMDARs regulate recruitment of cytoplasmic NMDAR and AMPA receptor subunits to nascent postsynaptic sites; (4) pharmacological blockage of NMDAR will prevent the insertion of NR1/NR2A heteromers of NMDAR and AMPA receptors 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 somatosensory 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.