Cellular and molecular mechanisms underlying anesthetic actions and neurotoxicity

麻醉作用和神经毒性的细胞和分子机制

• 批准号: RGPIN-2020-05307
• 负责人: Syed, Naweed
• 金额: $ 2.91万
• 依托单位: University of Calgary
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=740499
• 关键词: Cellular; molecular; mechanisms; underlying; anesthetic

Evidence suggests that most commonly used local (Propofol e.g.) and inhalation (sevoflurane, desflurane etc) anesthetic agents may exert long-term side effects leading to neurotoxicity and learning and memory deficits in animals, however a direct evidence is still lacking. My research program, supported by NSERC has been focused at defining the cellular and molecular mechanisms underlying anesthetic-induced neurotoxicity - in both snail and rat models. Notwithstanding these advances, however there remain significant gaps in our knowledge vis-à-vis:a) the potential target sites for anesthetic-induced neurotoxicity, b) how best to prevent anesthetic-induced insult to neurons, and c) to develop novel anesthetic compounds that are least toxic and more efficacious. We have four specific aims with well-defined objectives that will address these issues directly. Aim #1: To determine whether P110 peptide mitigates anesthetic-induced neuronal toxicity in cultured Lymnaea and rat neurons. We have demonstrated that anesthetics-induced neurotoxicity involves perturbation of synaptic proteins as well as mitochondrial structure and function. Whereas the neurotoxic effects were reversed with a mitochondrial fusion inhibitor Mdivi-1, this compound is however non-specific and may itself be neurotoxic if used in live animals. We now wish to demonstrate that prior exposure of cultured neurons to P110 peptide will prevent anesthetic induced cell death, suppression of neurite outgrowth and synaptic proteins structure and function. Aim #2: To demonstrate anesthetic-induced toxicity in the intact rat brain slices. We will use our newly developed and patented 3-D chip (NSERC), and the isolated hippocampal brain slices will be interfaced to monitor synaptic plasticity at the CA3-CA1 synapse. This study will provide the first direct evidence that indeed anesthetics perturb neuronal communications and synaptic plasticity in the intact brain slices. We will then use P110 peptide to block anesthetic induced toxicity. Aim #3: To demonstrate whether exposure of pregnant female rats affects learning and memory in the new born pups. We will expose either pregnant rats or their new born pups (P2-P12) to sevoflurane, desflurane, propofol etc. for 20-30 minutes and their vital signs will be monitored throughout. 4-8 weeks post exposure, we will test these animals with various learning and memory tasks (novel object recognition, water maze, fear conditioning, Morris Water maze etc). Control air or saline injected animals will be used as controls. Aim #4: To mitigate anesthetic-induced deficit in learning and memory with P110 peptide. We will seek to mitigate anesthetic-induced effects on cognition and learning and memory by pre-treating the pups with P110. We anticipate that the peptide will rescue animals from anesthetic induced cytotoxicity. Together these studies will forge novel understanding of mechanisms underlying anesthetic-induced toxicity and reveal mitigation strategies.

有证据表明，最常用的局部麻醉（如丙泊酚）和吸入（七氟烷、地氟烷等）麻醉剂可能产生长期副作用，导致动物神经毒性和学习记忆缺陷，但仍缺乏直接证据。我的研究计划，由NSERC支持，一直专注于定义麻醉诱导的神经毒性的细胞和分子机制-在蜗牛和大鼠模型。尽管取得了这些进展，但我们在以下方面的知识仍存在重大差距：a）麻醉剂诱导的神经毒性的潜在靶位点，B）如何最好地防止麻醉剂诱导的神经元损伤，以及c）开发毒性最小且更有效的新型麻醉剂化合物。我们有四个明确的目标，这些目标将直接解决这些问题。目的#1：确定P110肽是否减轻培养的神经元和大鼠神经元中麻醉诱导的神经元毒性。我们已经证明，麻醉剂诱导的神经毒性涉及突触蛋白以及线粒体结构和功能的扰动。而线粒体融合抑制剂Mdivi-1逆转了神经毒性作用，但该化合物是非特异性的，如果用于活体动物，其本身可能具有神经毒性。我们现在希望证明，培养的神经元预先暴露于P110肽将防止麻醉诱导的细胞死亡，抑制轴突生长和突触蛋白的结构和功能。目的#2：证明完整大鼠脑切片中的麻醉诱导毒性。我们将使用我们新开发的专利3-D芯片（NSERC），分离的海马脑切片将被连接到CA 3-CA 1突触处监测突触可塑性。这项研究将提供第一个直接证据，证明麻醉剂确实干扰了完整脑切片中的神经元通信和突触可塑性。然后我们将使用P110肽来阻断麻醉剂诱导的毒性。目的#3：证明妊娠雌性大鼠的暴露是否影响新生幼崽的学习和记忆。我们将使妊娠大鼠或其新生幼仔（P2-P12）暴露于七氟烷、地氟烷、丙泊酚等20-30分钟，并在整个过程中监测其生命体征。4-8在暴露后10周，我们将用各种学习和记忆任务（新物体识别、水迷宫、恐惧条件反射、Morris水迷宫等）测试这些动物。对照空气或盐水注射动物将用作对照。目的#4：用P110肽减轻麻醉诱导的学习和记忆缺陷。我们将通过用P110预处理幼仔来寻求减轻麻醉诱导的对认知、学习和记忆的影响。我们预期该肽将使动物免于麻醉剂诱导的细胞毒性。这些研究将共同建立对麻醉诱导毒性机制的新理解，并揭示缓解策略。