Toxic Effects of Anesthetics in Developing White Matter

项目摘要 基于人类流行病学研究和动物研究中获得的最佳证据 在啮齿类动物和非人类灵长类动物中进行的研究中，美国食品和药物管理局已经发出警告， 反复和/或长时间暴露于麻醉剂和镇静剂药物之间的第三个三个月和 三岁的孩子可能会影响大脑发育。这些短效药物 可能产生的长期后果尚不清楚。几乎所有以前关于这个问题的研究都是 神经元，然而，大脑回路的正常运作也严重依赖于其他细胞类型。 在哺乳动物物种的胎儿和出生后发育过程中，少突胶质细胞（OL）从 少突胶质细胞前体细胞（OPC），并产生髓鞘，隔离轴突，以确保高保真 电信号的传输。因此，开发OL代表了一个高度合理的， 麻醉剂神经毒性的新靶点。我们建议测试中心假设，早期 全身麻醉（GA）的发育暴露通过破坏髓鞘来干扰大脑发育 阵首先，我们将通过确定哪些常用的遗传算法来评估这一假设的总体影响 干扰髓鞘形成，鉴定由髓鞘形成受损引起的GA诱导的神经功能缺损，以及 测试GA对人类OL发育的影响。我们的初步数据表明，气体干扰， OPCs的功能，OPCs是一种前体细胞库，对发育至关重要 髓鞘形成因此，我们将检验GAs通过抑制存活在细胞水平上起作用的假设， OPCs的增殖、分化和/或稳态相互作用。最后，我们将测试假设， GAs通过抑制调节DNA序列的甲基化在分子水平上发挥表观遗传效应， 髓鞘形成所需基因的转录。为了解决这些问题，我们的研究将采用创新的， 尖端的实验神经科学工具，包括人类胚胎干细胞，条件性转基因 小鼠，双光子体内真实的时间成像和细胞消融，以及高通量测序。 甲基化这一建议的实验有望确定一种全新的麻醉机制 毒性成人神经系统概括了髓鞘发育的许多要素，作为神经系统的关键部分。 防御脱髓鞘疾病如多发性硬化症和肌萎缩性脊髓炎的破坏性影响， 脊髓侧索硬化症和作为一个关键的特点，从致残性损伤，如脑外伤和中风恢复。 因此，我们的研究结果将对怀孕患者和幼儿以及大规模人群具有重要意义 髓鞘相关病理的成年患者。对麻醉剂如何影响髓鞘的进一步了解 这里获得的信息将使研究人员能够设计评估麻醉剂和/或镇静剂风险的研究， 潜在易感患者的暴露情况，并测试预防和治疗策略以减轻伤害 给那些有风险的病人。

PROJECT SUMMARY Based on the best available evidence derived from human epidemiologic studies and animal research conducted in rodents and non-human primates, the U.S. Food and Drug Administration has issued a warning that repeated and/or lengthy exposures to anesthetic and sedative drugs between the third trimester and the third year of life may adversely affect brain development. The mechanism by which these short-acting drugs could have long-term consequences remains unclear. Nearly all previous research on this topic has been focused on neurons, however proper functioning of brain circuitry is also heavily dependent on other cell types. During fetal and postnatal development across mammalian species, oligodendrocytes (OLs) differentiate from oligodendrocyte precursor cells (OPCs) and generate myelin, which insulates axons to ensure high-fidelity transmission of electrical signals. Therefore, developing OLs represents a highly plausible and largely unexplored novel target for anesthetic neurotoxicity. We propose to test the central hypothesis that early developmental exposure to general anesthesia (GA) interferes with brain development by disrupting myelin formation. First, we will assess the overall impact of this hypothesis by determining which commonly used GAs interfere with myelination, identifying GA-induced neurologic deficits that result from impaired myelination, and testing the effects of GAs on human OL development. Our preliminary data suggests that GAs interfere with the function of OPCs, which are a pool of precursor cells that are critically important for developmental myelination. Thus, we will test the hypothesis that GAs act at the cellular level by inhibiting the survival, proliferation, differentiation, and/or homeostatic interactions of OPCs. Finally, we will test the hypothesis that GAs exert an epigenetic effect at the molecular level by inhibiting methylation of DNA sequences that regulate transcription of genes required for myelination. To address these questions, our study will employ innovative, cutting-edge experimental neuroscience tools, including human embryonic stem cells, conditional transgenic mice, two-photon in vivo real time imaging and cell ablation, and high throughput sequencing of the methylome. The experiments of this proposal are expected to define an entirely new mechanism of anesthetic toxicity. The adult nervous system recapitulates many elements of myelin development as a critical part of the defense against the devastating effects of demyelination disorders such as multiple sclerosis and amyotrophic lateral sclerosis and as a key feature of recovery from disabling injuries such as brain trauma and stroke. Thus, our findings will be significant for pregnant patients and young children, and also for the large population of adult patients with myelin-related pathology. The enhanced understanding of how anesthetics affect myelin formation gained here will allow researchers to design studies assessing the risks of anesthetic and/or sedative exposures in potentially vulnerable patients and to test preventative and treatment strategies to mitigate harm to those patients who are at risk.