Plasticity N-Type Ca2+ Channels in Sympathetic Neurons

交感神经元中的可塑性 N 型 Ca2 通道

• 批准号: 6529159
• 负责人: Ann R. Rittenhouse
• 金额: $ 27.83万
• 依托单位: UNIV OF MASSACHUSETTS MED SCH WORCESTER
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-06-01 至 2006-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6529159
• 关键词: G protein; arachidonate; calcium channel; laboratory rat; neural plasticity; neurotransmitters; phosphorylation; protein kinase C; protein structure function; sympathetic ganglion

DESCRIPTION (provided by applicant): The long-term goal of this lab is to identify sources of plasticity at the level of single proteins. Our working definition of plasticity at this level is the ability of a protein's behavior to vary, not simply due to an increase or decrease in its activity as with acute activation of an enzyme, but rather by qualitative changes in its behavior. Single N-type Ca channels display heterogeneous activity, called modes, where unitary conductance and kinetics are stable for seconds to minutes before abruptly changing to a new pattern of activity. Because the transitions among modes result in qualitative changes in N-type Ca channel activity, they can be considered plastic proteins. The N-type calcium (Ca) channel is found only in nerve cells and neuronally-derived tissues. It is the most extensively modulated Ca channel in the brain in that more pathways exist for its modulation than for any other, and because of this, it is thought to play a critical role in synaptic plasticity. The proposed experiments test the hypothesis that transmitters exert their actions on N-type Ca channels by activating signaling molecules that shift channel activity from one mode to another. The specific aims of this project are the following: 1) confirm that phosphorylation of the N-type Ca channel by protein kinase C (PKC) stabilizes an inactivating mode with long openings; 2) determine whether G-proteins protect channels from inactivation; 3) determine whether arachidonic acid (AA)-induced inhibition stabilizes a null activity mode; 4) demonstrate that transmitters, use PKC and AA to modulate N-type currents. Whole cell and unitary N-type currents will be studied with standard patch clamp techniques in superior cervical ganglion neurons, a preparation rich in N-type Ca channels. The effects of signaling molecules on current amplitude, gating kinetics, and rates of transition between different modes will be analyzed quantitatively. We expect to find that transmitters do converge on these signaling molecules to modulate Ca currents by stabilizing particular modes. If true, plasticity of N-type Ca channels may be a building block for emergent forms of plasticity, observed at synapses and in neural circuits. Moreover, these results should establish new signal transduction cascades for N-type Ca channel modulation, which may also be present in central neurons. Further understanding of the modulation of N-type Ca channel modes might allow the design of new pharmaceutical agents that act to stabilize modes which alter net Ca influx. This could help minimize cytotoxicity that can occur during cerebral vasospasm, stroke, epilepsy; and reduce mobility from cognitive, and/or learning and memory disorders.

描述（由申请人提供）：该实验室的长期目标是 在单蛋白水平上识别可塑性来源。我们的工作 在此级别的可塑性的定义是蛋白质行为的能力 不同的是，不仅是由于其活动的增加或减少 酶的急性激活，而是通过其定性变化 行为。单n型CA通道显示异质活动，称为 模式，单位电导和动力学稳定持续几秒钟到几分钟 在突然更改为新的活动模式之前。因为过渡 在模式中导致N型CA通道活动的质量变化，它们 可以被视为塑料蛋白。发现N型钙（CA）通道 仅在神经细胞和神经源性组织中。它是最广泛的 大脑中的调制CA渠道在其中存在更多的途径 调制而不是其他任何人，因此，人们认为它可以发挥 在突触可塑性中的关键作用。提出的实验测试了 通过发射机在N型CA通道上发挥作用的假设 激活信号分子将通道活性从一种模式转移到 其他。该项目的具体目的是：1）确认 通过蛋白激酶C（PKC）稳定N型Ca通道的磷酸化 一个灭活模式，有较长的开口； 2）确定是否G蛋白 保护渠道免于失活； 3）确定蛛网酸是否 （AA）诱导的抑制作用稳定了无效活性模式； 4）证明这一点 发射器，使用PKC和AA调节N型电流。全细胞和 将使用标准贴片夹技术研究单位n型电流 上宫颈神经神经元，富含N型CA通道的制剂。 信号分子对当前幅度，门控动力学和 不同模式之间的过渡速率将进行定量分析。我们 希望发现发射器确实会在这些信号分子上收敛到 通过稳定特定模式来调节CA电流。如果是真的，则可塑性 N型CA通道可能是新兴形式可塑性的基础， 在突触和神经回路中观察到。而且，这些结果应该 为N型CA通道调制建立新的信号转导级联 中央神经元中也可能存在。进一步了解 N型CA通道模式的调制可能允许设计新的 起作用的药物可以稳定改变净CA涌入的模式。 这可能有助于最大程度地减少脑血管痉挛期间可能发生的细胞毒性， 中风，癫痫；并减少认知和/或学习的流动性和 记忆障碍。