SECOND MESSENGER SYSTEMS ON THE ACTIONS OF A-BETA ON HIPPOCAMPAL NEURONS

纤维β-淀粉样肽(Abeta)的沉积，主要 淀粉样斑块的成分，被大多数核心理论认为是 阿尔茨海默病(AD)是选择性神经炎的关键因素 营养不良和神经元变性。Abeta的胞外沉积 被认为是AD病理的原因之一。神经学 纤维缠结、细胞丢失、血管损伤和痴呆 被推定为这一证词的直接结果。因此， 阿尔茨海默病的大部分研究都集中在了解 Abeta生成，关于发现影响Abeta聚集的因素和 沉积和识别Abeta在细胞内的作用 水平。我们对Abeta的影响的大部分理解 细胞事件源于对培养的胚胎神经的研究 细胞，一种处于其成熟早期阶段的制剂，不能 与通常死于阿尔茨海默病的成熟神经元非常相似。在……里面 相比之下，初步实验将构成 建议的研究是在严重分离的成人或老年人中获得的。 海马神经元。在这些细胞中，细胞内的第二信使- 相关通路似乎介导了抗体的快速细胞效应，可能 这是聚合的一些病理后果的基础 多肽。神经元对阿贝塔斯的急性暴露显著增加 NMDA通道通过一种不同于已知的调制途径发挥作用 阿贝塔斯的作用包括增加钙内流、释放游离 自由基，或速激肽受体的激活。基于这些 根据调查结果，本提案将处理以下假设： 细胞内第二信使通路，包括蛋白激酶或 在成年或老年神经元中，磷酸酶被Abeta激活。这 该项目有四个具体目标：1)确定蛋白激酶和 由Abeta激活或抑制的磷酸蛋白磷酸酶；2) 确定Abeta是否激活了与其他系统相同的第二信使系统 多肽受体；3)确定钙通道蛋白的作用和贡献 Abeta的细胞和毒性作用；以及4)揭示可能的 G蛋白和环GMP在细胞内的作用 阿贝塔。这项研究将使用高分辨率电生理 成年啮齿动物中枢神经系统神经元的体外记录和协作 与Frautschy博士一起，它将评估Abeta造成的细胞损害 体内给药对小鼠脑内的影响 细胞内钙结合蛋白钙结合蛋白(CB)和小白蛋白(PV)。 通过解决Abeta对细胞第二信使的影响 成年和老年海马神经细胞的功能及其研究 Abeta对细胞第二信使功能的这些新作用 成年和老年海马神经细胞，并研究这些新的 Abeta对发育完全和老年人群NMDA通道活性的影响 神经元这一提议将识别细胞内的第二信使 可能与Abeta的作用有关的通路。激活 从长远来看，由Abeta引起的第二信使级联可能导致 与神经元功能障碍和最终的变性相关 使用AD。

Deposition of fibrillary beta-amyloid peptide (Abeta), the main component of amyloid plaques, is considered by most uccrent theories on Alzheimer's disease (AD) to be a key factor in the selective neuritic dystrophy and neuronal degeneration. Extracellular deposition of Abeta is thought to be one of the causes of AD pathology. The neural fibrillary tangles, cell loss, vascular damage, and dementia are presumed to follow as a direct result of this deposition. Accordingly, much of AD research focuses on understanding the molecular pathways for Abeta generation, on discovering factors affecting Abeta aggregation and deposition and on identifying the effects of Abeta at the cellular level. Most of our understanding concerning the effects of Abeta on cellular events is derived from research on cultured embryonic nerve cells, a preparation in an early stage of its maturation that cannot adequately resemble mature neurons that usually succumb to AD. In contrast, the preliminary experiments which will constitute the basis of the proposed studies, were obtained in acutely dissociated adult or aged hippocampal neurons. In these cells, intracellular second messenger- related pathways appear to mediate rapid cellular effects of Ab that may underlie some of the pathological consequences of the aggregated peptide. Acute exposure of the neurons to Abetas dramatically enhanced NMDA channel function through a modulatory pathway distinct from known effects of Abetas including elevated Ca2+ influx, liberation of free radicals, or activation of tachykinin receptors. Based on these findings, the present proposal will address the following hypothesis: intracellular second messenger pathways, including protein kinases or phosphatases, are activated by Abeta in adult or aged neurons. This project has four specific aims: 1) to identify protein kinases and phosphoprotein phosphatases activated or inhibited by Abeta; 2) to ascertain whether Abeta activates 2nd messenger systems common to other peptide receptors; 3) to determine the role and contribution of Ca2+ in the cellular and toxic actions of Abeta; and 4) to reveal the possible involvement of G-proteins and cyclic GMP in the cellular actions of Abeta. The study will use high resolution electrophysiological recordings in vitro in adult rodent CNS neurons, and in collaboration with Dr. Frautschy, it will assess the cellular damage produced by Abeta administration in vivo into the brains of mice null mutant for the intracellular Ca2+-binding proteins calbindin (CB) and parvalbumin (PV). By addressing the effects of Abeta on cellular second messenger functions in adult and aged nerve cells of the hippocampus and studying these novel actions of Abeta on cellular second messenger functions in adult and aged nerve cells of the hippocampus, and studying these novel actions on Abeta on NMDA channel activity in fully developed and aged neurons this proposal will identify intracellular second messenger pathways possibly involved in the actions of Abeta. An activation of second messenger cascades by Abeta may cause may lead, in the long run, to the neuronal dysfunction and the eventual degeneration associated with AD.