DEVELOPMENT AND MODULATION OF CALCIUM CURRENTS IN CORTEX

在出生后的早期，哺乳动物的皮层经历了快速的 细胞特性、层状结构和突触的变化 连通性。 这些特性的适当成熟对于 正常的大脑功能，和大脑的几种疾病可能反映 发育的异常模式（例如精神分裂症，癫痫， 抑郁症）。 这些变化中的许多对突触的模式很敏感， 输入和细胞活动的程度。 增加细胞内 Ca 2+水平被认为是一个重要的机制， 行为和突触输入的模式被转化为变化， 突触强度或连接性。 在成年的皮质锥体细胞中， 几种离子电导相互作用以形成细胞的活性。 这种相互作用在成体细胞中还不完全清楚， 在未成熟的神经元中检测。 神经调节剂如去甲肾上腺素（NE）和5-羟色胺（5 HT）激活 G蛋白和第二信使系统改变离子电导， 成年神经元的放电行为 这些发射机系统成熟于 与金字塔的内在细胞特性相同的时间段 细胞，并可能影响皮质可塑性。 我们设计了 研究Ca 2+和Ca依赖性K+的性质的实验 不同日龄大鼠脑内去甲肾上腺素和5-羟色胺的作用 感觉运动皮质锥体神经元。 核心假设驱动 本文认为NE和5 HT具有多重聚散性 对未成熟和成年新皮层电压门控性钙电流的影响 锥体细胞 此外，这些影响可能与年龄有关， Ca 2+和K+通道表达的发育变化， NE和5 HT受体，以及Ca 2+调节的成熟 机制等 本研究的具体目的是：（1）研究个体发育 新皮质神经元中不同Ca 2+电流的变化。 (2)确定 参与NE调节Ca 2+电流的信号通路， 5 HT。 (3)确定不同Ca 2+电流的功能作用 在诱发钙依赖性钾电流和超极化后。 我们 将在脑切片制备中使用细胞内记录， 来自急性分离的神经元的细胞膜片钳记录， 药理学试剂和单细胞mRNA扩增技术。 从这些实验中获得的数据有望有助于 了解（1）离子通道的发展，以及（2） NE和5 HT对钙电流和细胞整合的调节作用 皮质锥体细胞 这些机制可能很重要 在正常皮质功能的发展中，以及在疾病中， 流程.

During the early postnatal period, the mammalian cortex undergoes rapid changes in cellular properties, laminar structure, and synaptic connectivity. Proper maturation of these properties is essential to normal brain function, and several diseases of the brain may reflect abnormal patterns of development (e.g. schizophrenia, epilepsy, depression). Many of these changes are sensitive to patterns of synaptic input and the degree of cellular activity. Increases in intracellular Ca2+ levels are thought to be an important mechanism by which firing behavior and the pattern of synaptic inputs are translated into changes in synaptic strength or connectivity. In adult cortical pyramidal cells, several ionic conductances interact to shape the activity of the cell. This interplay is incompletely understood in adult cells and even less examined in immature neurons. Neuromodulators such as norepinephrine (NE) and serotonin (5HT) activate G-proteins and second messenger systems to alter ionic conductances and firing behavior in adult neurons. These transmitter systems mature over the same time period as the intrinsic cellular properties of pyramidal cells, and may influence cortical plasticity. We have designed experiments to investigate the properties of Ca2+ and Ca-dependent K+ currents, and the effects of NE and 5HT at various postnatal ages in rat sensorimotor cortical pyramidal neurons. The central hypothesis driving this work is that NE and 5HT have multiple convergent and divergent effects on voltage-gated Ca2+ currents in immature and adult neocortical pyramidal cells. Furthermore, these effects may be age-dependent due to developmental changes in the expression of Ca2+ and K+ channels and receptors for NE and 5HT, as well as in the maturation of Ca2+ regulatory mechanisms. The Specific Aims of this proposal are (1) To investigate the ontogeny of different Ca2+ currents in neocortical neurons. (2) To determine the signalling pathways involved in the modulation of Ca2+ currents by NE and 5HT. (3) To determine the functional roles of different Ca2+ currents in eliciting Ca-dependent K+ currents and after hyperpolarizations. We will employ intracellular recordings in a brain slice preparation, whole cell patch clamp recordings from acutely dissociated neurons, pharmacological agents, and single cell mRNA amplification techniques. Data derived from these experiments are expected to help in the understanding of (1) the development of ion channels, and (2) the actions of NE and 5HT in modulating Ca2+ currents and cellular integration in cortical pyramidal cells. These mechanisms are likely to be important in the development of normal cortical function, as well as in disease processes.