Cognitive effects of anesthetics and dopamine transport

描述(由申请者提供)：此资助是作为回应而提交的 到节目公告，PA-96-026，“麻醉剂的分子药理学” 行动。“公告说(部分)。”它一直很难 指定受以下因素影响的分子事件之间的直接关联 麻醉剂和随后发生的生理效应。 初步数据部分，我们提供了分子相互作用的证据 挥发性麻醉剂和多巴胺转运体(DAT)。我们的模式是： 最初，在表达的和细胞质(DAT)之间存在正常运输。 在麻醉诱导时，一些麻醉剂直接与DAT结合，一些麻醉剂 激活蛋白激酶C(PKC)，导致DAT的一些内化。这个 由于表达DAT结果的较少，细胞外DA浓度增加 对DA的再摄取较少。DA的持续释放受到反馈的抑制 细胞外多巴胺发出信号的机制。在长时间的麻醉期间， 细胞外DA被代谢，从而降低了它的浓度，而 提高其代谢物的浓度。麻醉停止后， 麻醉剂首先从体内清除，允许表达的DAT 函数和PKC返回到非活动状态。然后，DA浓度开始 来恢复健康。在系统接近恢复后，DAT和细胞外DA 浓度恢复正常，但必须合成额外的DA以 补充因新陈代谢而失去的营养。认知能力终究会正常化 各子系统恢复到基准值。我们建议使用一个 一系列体外、大鼠、非人灵长类和人类研究，并确定 这些变化的生理意义，因为它们与认知有关 通过3个具体目标在人类身上表现：具体目标1：分析 DAT-麻醉剂在细胞和亚细胞水平上的相互作用。我们 假设DAT-麻醉剂的相互作用在临床上具有重要意义 某些麻醉剂的相关浓度，我们预计会减少 麻醉给药后FECNT结合和[~3H]多巴胺摄取 由于转运蛋白的内部化。具体目标2：确定 DAT-麻醉剂在完整的活体组织中的相互作用。我们希望确认DAT 内化并观察到细胞外DA的初始增加，随后 DA减少和代谢物增加表明 达特。与目标1相比，这些实验的结果将确定 与其他神经系统的互动很重要。他们还将提供一个 直接校准以解释目标3中的正电子发射计算机断层扫描结果。具体目标3： 测量以下[18F]FECNT结合电位降低的持续时间 麻醉作用于人类，并与认知功能相关。使用 来自目标1和目标2的结果，此PET实验将提供有关DAT的信息 麻醉后人类的表达。我们预计时间进程将是 归一化结合电位与认知成绩的相关性 井。

Description (provided by applicant): This grant is being submitted in response to the program announcement, PA-96-026, "Molecular Pharmacology of Anesthetic Action." The announcement states (in part) ." . .it has been difficult to assign a direct correlation between molecular events that are influenced by anesthetics and the physiological effects that subsequently occur." In the preliminary data section, we present evidence of molecular interaction between volatile anesthetics and the dopamine transporter (DAT). Our model is: Initially, there is normal trafficking between expressed and cytoplasmic (DAT). At induction of anesthesia, some anesthetic binds directly to the DAT and some activates protein kinase C (PKC) causing some internalization of DAT. The extracellular concentration of DA increases because fewer expressed DAT result in less reuptake of DA. Continued release of DA is inhibited by a feedback mechanism signaled from extracellular DA. During prolonged anesthesia, the extracellular DA is metabolized, which decreases its concentration while increasing the concentration of its metabolites. After cessation of anesthesia, the anesthetic first clears from the body allowing the expressed DAT to function and PKC to return to the inactive state. Then, DA concentration begins to recover. After the system has nearly recovered, the DAT and extracellular DA concentrations return to normal but additional DA must be synthesized to replenish that lost to metabolism. Cognitive ability normalizes after all subsystems return to baseline values. We propose to test this model with a series of in vitro, rat, non-human primate and human studies and to determine the physiological significance of these changes as they relate to cognitive performance in humans through 3 specific aims: Specific Aim 1: Analyze the DAT-anesthetic interaction at the cellular and sub-cellular level. We hypothesize that DAT-anesthetic interaction will be significant at clinically relevant concentrations for certain anesthetics and, we expect to see reduced [18F]FECNT binding and [3H]dopamine uptake following anesthetic administration due to trasnporter internalization. Specific Aim 2: Characterize the DAT-anesthetic interaction in intact living tissue. We expect to confirm DAT internalization and observe an initial increase in extracellular DA followed by decreased DA and increased metabolites indicating decreased functioning of the DAT. Results of these experiments in comparison with aim 1 will determine if interaction with other neural systems is important. They will also provide a direct calibration for interpreting the PET results in aim 3. Specific Aim 3: Measure the duration of decreased [18F]FECNT binding potential following anesthesia in humans and correlate with cognitive functioning. Using the results from aims 1 and 2, this PET experiment will give information about DAT expression in humans following anesthesia. We expect the time course to normalization of the binding potential and cognitive performance to correlate well.