NMDA RECEPTOR IN LEAD INDUCED COGNITIVE DEFICIT

铅引起的认知缺陷中的 NMDA 受体

• 批准号: 2838208
• 负责人: Edson X. Albuquerque
• 金额: $ 18.77万
• 依托单位: UNIVERSITY OF MARYLAND BALTIMORE
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-06-01 至 2001-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2838208
• 关键词: NMDA receptors; aminoacid inhibitor; cerebrospinal fluid; cognition disorders; excitatory aminoacid; extracellular; hippocampus; inhibitor /antagonist; laboratory rat; lead; lead poisoning; neurotoxicology; nicotinic receptors; receptor expression; synapses

DESCRIPTION: The goal of this project is to understand the mechanisms by which lead (Pb2+) exerts neurotoxic effects in the central nervous system (CNS) particularly in the developing brain. N-methyl-D-aspartate (NMDA) receptor-ion channels (nAChRs) are very sensitive to inhibition by Pb2+. Whereas the inhibitory effect of Pb2+ on NMDA receptors is apparently due to its action on a Ca2+ site on the receptor, the mechanisms by which Pb2+ inhibits the activation of the alpha7-bearing nAChRs is still unknown and will be investigated in this proposal. Because NMDA receptors and alpha7-bearing nAChR are involved in memory and learning as well as in other forms of neuronal plasticity and development, it is very likely that inhibition of these receptors by Pb2+, particularly during early stages of neuronal maturation, could be associated with the severe learning disabilities caused by this heavy metal. Considering that distal dendritic development of the hippocampal neurons is particularly sensitive to the toxic effects of Pb2+, and that dendritic development(with formation and maturation of dendritic spines) is associated with learning and memory, the following question is raised: Is the expression of Pb2+-sensitive NMDA receptors and nAChRs restricted during development to particular neuronal regions, such as apical and basal dendrites, in distinct hippocampal areas (CA1, CA3, or dentate gyrus)? To answer this questions we will use state-of-the-art infrared microscopy (which allows visualization of axons, dendrites, and dendritic spines) combined with a computer-driven, robotic system of micromanipulators (which enables us to control the positions of patch electrodes and drug-delivery systems at precisely defined regions on the neuronal surfaces). Recordings can then be made of whole-cell and single-channel currents from neurons either visualized in or acutely dissociated from hippocampi of rats at different ages, and we will be able to map the distribution of Pb2+-sensitive nicotinic and NMDA receptors on cell bodies, dendrites, and dendritic spines of hippocampal neurons. Our preliminary studies also indicate that Pb2+ substantially increases spontaneous transmitter release from hippocampal neurons. Taking into account that NMDA receptors and alpha-BGT-sensitive nAChRs present on presynaptic terminals of CNS neurons can modulate the release of a number of neurotransmitters, it is critical to determine whether Pb2+ alters transmitter release by acting at these presynaptic receptors. Therefore, the effects of Pb2+ on spontaneous and evoked transmitter release will be investigated at the level of single synapses on hippocampal neurons, which will be acutely dissociated at various stages of development. We have developed a technique by which neurons can be acutely dissociated by mechanical means (without enzyme treatment) from hippocampi of rats at various ages. These neurons bear many synaptic terminals that are functional and can be electrically stimulated. Altogether these studies should provide the foundation for an understanding of the net effects of Pb2+ on receptor function, synaptic activation and maturation in the developing CNS.

描述：该项目的目标是通过以下方式了解其机制： 铅（Pb2+）对中枢神经系统产生神经毒性作用 （中枢神经系统）特别是在发育中的大脑中。 N-甲基-D-天冬氨酸 (NMDA) 受体离子通道 (nAChR) 对 Pb2+ 的抑制非常敏感。 而 Pb2+ 对 NMDA 受体的抑制作用显然是由于 它对受体上 Ca2+ 位点的作用，Pb2+ 的机制 抑制带有 α7 的 nAChR 的激活仍然未知，并且 将在本提案中进行调查。 因为 NMDA 受体和 带有 α7 的 nAChR 参与记忆和学习以及其他 神经元可塑性和发育的形式，很可能是 Pb2+ 对这些受体的抑制，特别是在早期阶段 神经元的成熟，可能与剧烈的学习有关 这种重金属造成的残疾。 考虑到远端树突 海马神经元的发育对 Pb2+ 的毒性作用，以及树突的发育（随着形成和 树突棘的成熟）与学习和记忆有关， 提出以下问题： Pb2+ 的表达是否对 NMDA 敏感 受体和 nAChR 在发育过程中受限于特定神经元 不同海马区域的区域，例如顶端和基底树突 （CA1、CA3 或齿状回）？ 为了回答这个问题，我们将使用 最先进的红外显微镜（可以实现轴突的可视化， 树突和树突棘）与计算机驱动的机器人相结合 微操纵器系统（它使我们能够控制 贴片电极和药物输送系统位于精确定义的区域 神经元表面）。 然后可以对全细胞和 来自神经元的单通道电流，无论是可视化的还是敏锐的 从不同年龄的大鼠的海马体中分离出来，我们将能够 绘制 Pb2+ 敏感烟碱和 NMDA 受体的分布图 海马神经元的细胞体、树突和树突棘。 我们的 初步研究还表明 Pb2+ 大幅增加 海马神经元自发释放递质。 考虑到 考虑到 NMDA 受体和 α-BGT 敏感的 nAChR 存在于 中枢神经系统神经元的突触前末梢可以调节多种神经元的释放 神经递质，确定 Pb2+ 是否改变至关重要 通过作用于这些突触前受体来释放递质。 所以， Pb2+ 对自发和诱发递质释放的影响为 在海马神经元的单个突触水平上进行了研究， 在不同的发展阶段，会出现严重的分离。 我们有 开发了一种可以使神经元急剧解离的技术 机械方法（未经酶处理）来自大鼠海马 各个年龄段。 这些神经元具有许多突触末端 有功能并且可以被电刺激。 总共这些研究 应为理解净效应提供基础 Pb2+ 对受体功能、突触激活和成熟的影响 发展中枢神经系统。

项目成果

9-Aminoacridines act at a site different from that for Mg2+ in blockade of the N-methyl-D-aspartate receptor channel.

9-氨基吖啶的作用位点与 Mg2 不同，可阻断 N-甲基-D-天冬氨酸受体通道。

• 发表时间: 1994
• 期刊: Molecular pharmacology
• 影响因子: 3.6
• 作者: Nelson,ME;Albuquerque,EX
• 通讯作者: Albuquerque,EX

Neuronal nicotinic receptors modulate synaptic function in the hippocampus and are sensitive to blockade by the convulsant strychnine and by the anti-Parkinson drug amantadine.

神经元烟碱受体调节海马突触功能，并且对惊厥药士的宁和抗帕金森病药物金刚烷胺的阻断敏感。

• DOI: 10.1016/s0378-4274(98)00309-9
• 发表时间: 1998
• 期刊: Toxicology letters
• 影响因子: 3.5
• 作者: Albuquerque,EX;Pereira,EF;Braga,MF;Matsubayashi,H;Alkondon,M
• 通讯作者: Alkondon,M

Choline and selective antagonists identify two subtypes of nicotinic acetylcholine receptors that modulate GABA release from CA1 interneurons in rat hippocampal slices.

胆碱和选择性拮抗剂鉴定了烟碱乙酰胆碱受体的两种亚型，它们调节大鼠海马切片中 CA1 中间神经元的 GABA 释放。

• DOI: 10.1523/jneurosci.19-07-02693.1999
• 发表时间: 1999
• 期刊: The Journal of neuroscience : the official journal of the Society for Neuroscience
• 作者: Alkondon,M;Pereira,EF;Eisenberg,HM;Albuquerque,EX
• 通讯作者: Albuquerque,EX

Diversity of nicotinic acetylcholine receptors in rat hippocampal neurons. III. Agonist actions of the novel alkaloid epibatidine and analysis of type II current.

大鼠海马神经元烟碱乙酰胆碱受体的多样性。

• 发表时间: 1995
• 期刊: The Journal of pharmacology and experimental therapeutics
• 作者: Alkondon,M;Albuquerque,EX
• 通讯作者: Albuquerque,EX

Physostigmine and galanthamine: probes for a novel binding site on the alpha 4 beta 2 subtype of neuronal nicotinic acetylcholine receptors stably expressed in fibroblast cells.

毒扁豆碱和加兰他敏：成纤维细胞中稳定表达的神经元烟碱乙酰胆碱受体 α 4 β 2 亚型上新结合位点的探针。

• 发表时间: 1994
• 期刊: The Journal of pharmacology and experimental therapeutics
• 作者: Pereira,EF;Alkondon,M;Reinhardt,S;Maelicke,A;Peng,X;Lindstrom,J;Whiting,P;Albuquerque,EX
• 通讯作者: Albuquerque,EX