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A mouse model linking anesthetic sensitivity to mitochondrial function

将麻醉敏感性与线粒体功能联系起来的小鼠模型

基本信息

批准号：
8628393
负责人：
Margaret Mary Sedensky
金额：
$ 54.14万
依托单位：
SEATTLE CHILDREN'S HOSPITAL
依托单位国家：
美国
项目类别：
财政年份：
2014
资助国家：
美国
起止时间：
2014-05-01 至 2018-02-28
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8628393
关键词：
A Mouse Absence of pain sensation Adverse effects Affect Anesthesia procedures Anesthetics Animal Model Animals Area Astrocytes Behavior Biology Brain region Caenorhabditis elegans Cells Child Complex Conscious Defect Dose Drug Design Electron Transport Functional disorder Future Genetic Glutamates Goals Halothane Health Human Hypersensitivity Invertebrates Investigation Isoflurane Ketamine Knock-out Knockout Mice Knowledge Laboratories Lead Link Mammals Measurement Measures Mediating Memory Mental Depression Mitochondria Mitochondrial Diseases Modeling Modern Medicine Molecular Monitor Mus Mutant Strains Mice Mutation Nematoda Neonatal Nervous system structure Neurons Newborn Animals Operative Surgical Procedures Organism Patients Pharmaceutical Preparations Phenotype Phylogeny Physiology Play Primates Reflex action Resistance Rodent Role Safety Supporting Cell Surgical incisions Synapses Synaptic Transmission System Tail Testing Unconscious State Wild Type Mouse Work animal data behavior change cell type cholinergic improved insight interest knockout animal man mitochondrial dysfunction mouse model neurotoxicity neurotransmission novel response synaptic function tool

项目摘要

DESCRIPTION (provided by applicant): A true enigma of modern medicine has persisted for over 150 years. How can volatile anesthetics, as a class of drugs, simultaneously cause a patient to reversibly lose consciousness, feel no pain, and have no memory of surgery? The mechanism by which volatile anesthetics (VAs) produce reversible loss of consciousness and render an organism insensate to a surgical incision remains an unsolved mystery. Our laboratory has exploited a very simple animal model, the nematode C. elegans, to investigate the molecular mechanisms of volatile anesthetic action. Previously, we demonstrated that mitochondrial complex I, an entry point of the electron transport chain, specifically controls the sensitivity of C. elegans to volatile anesthetics. We also found that complex I defects control anesthetic sensitivity in humans. We now have an exciting opportunity to extend those findings into mice using the knockout animal, Ndufs4. The Ndufs4 KO mice lack a subunit of complex I, which results in complex I dysfunction. We anesthetized young (PN23-27) Ndusf4 and wild-type (WT) mice with isoflurane or halothane. For either VA, the KO mice became unresponsive to a tail pinch at a dose 2.8-fold lower than for WT controls. These KO mice display the greatest change in VA sensitivity ever described in a mammal. We also measured the EC50s for loss of righting reflex (LORR) of the KO mice for anesthetics whose targets are well characterized. Surprisingly, the animals were actually resistant to the effects of ketamine. The effects of the complex I KO are specific in terms of anesthetic and not simply the result of generalized CNS depression. Complex I dysfunction causes hypersensitivity to volatile anesthetics across phylogeny. However, the question remains, how do complex I defects affect VA sensitivity. We hypothesize that complex I depression (i.e. energy depletion) leads to defective synaptic function in specific cell types, making them more susceptible to neuronal silencing by VAs. We will knock out Ndufs4 in GABAergic, cholinergic or glutamatergic neurons, in neuronal support cells known as astrocytes, as well as in specific regions of the brain. We will also perform electrophysiologic measurements of WT and mutant mice with and without volatile anesthetics. Our initial results indicate that the VA hypersensitivity in Ndufs4 mice is mediated through glutamatergic neurons. Our aims are to characterize which neurons and regions of the brain are important for the anesthetic phenotype of these animals, as well as to discover how basic neuronal physiology is altered in the KO animals. Our overarching goal is to understand how the VAs functions. We have linked mitochondrial function to behavior in VAs in worms, mice, and man, a finding the field must consider. Our proposed studies will tease out which cell types mediate the anesthetic response, and will give important insights into the basic mechanisms of action of VAs.

描述（由申请人提供）：一个真正的现代医学之谜已经持续了150多年。挥发性麻醉剂，作为一类药物，怎么会同时导致患者可逆地失去意识，感觉不到疼痛，并且没有手术记忆？挥发性麻醉药（VAs）产生可逆性意识丧失并使机体对手术切口失去知觉的机制仍然是一个未解之谜。我们的实验室利用一种非常简单的动物模型，线虫C. elegans，来研究挥发性麻醉作用的分子机制。之前，我们证明了线粒体复合体I，电子传递链的入口点，专门控制秀丽隐杆线虫对挥发性麻醉剂的敏感性。我们还发现复合物I缺陷控制着人类的麻醉敏感性。现在，我们有一个激动人心的机会，将这些发现扩展到使用基因敲除动物Ndufs4的小鼠身上。Ndufs4 KO小鼠缺乏复合物I的一个亚基，导致复合物I功能障碍。用异氟醚或氟烷麻醉幼龄（PN23-27） Ndusf4和野生型（WT）小鼠。对于任何一种VA， KO小鼠在比WT对照组低2.8倍的剂量下对夹尾没有反应。这些KO小鼠显示出在哺乳动物中所描述的最大的VA敏感性变化。我们还测量了KO小鼠的ec50，以确定其靶点的麻醉药的翻正反射（LORR）的丧失。令人惊讶的是，这些动物实际上对氯胺酮的作用有抵抗力。复合I KO的作用在麻醉方面是特异性的，而不仅仅是广泛性中枢神经系统抑制的结果。复合物I功能障碍导致整个系统对挥发性麻醉药过敏。然而，问题仍然存在，复合体I缺陷是如何影响VA灵敏度的。我们假设复合物I抑制（即能量消耗）导致特定细胞类型的突触功能缺陷，使它们更容易受到VAs神经元沉默的影响。我们将敲除gaba能、胆碱能或谷氨酸能神经元、被称为星形胶质细胞的神经元支持细胞以及大脑特定区域中的Ndufs4。我们还将对使用和不使用挥发性麻醉剂的WT和突变小鼠进行电生理测量。我们的初步结果表明，Ndufs4小鼠的VA超敏反应是通过谷氨酸能神经元介导的。我们的目标是描述哪些神经元和大脑区域对这些动物的麻醉表型很重要，以及发现KO动物的基本神经元生理学是如何改变的。我们的首要目标是了解虚拟助手的功能。我们已经将线粒体功能与蠕虫、小鼠和人类的VAs行为联系起来，这是该领域必须考虑的发现。我们提出的研究将梳理出哪些细胞类型介导麻醉反应，并将为VAs的基本作用机制提供重要见解。