Department of Physiology, Faculty of Medicine, University of the Republic, Montevideo, Uruguay.
Department of Anesthesiology, University of Michigan, Ann Arbor, Michigan, USA.
Eur J Neurosci. 2024 Feb;59(4):483-501. doi: 10.1111/ejn.15690. Epub 2022 May 22.
Urethane is a general anaesthetic widely used in animal research. The state of urethane anaesthesia is unique because it alternates between macroscopically distinct electrographic states: a slow-wave state that resembles non-rapid eye movement (NREM) sleep and an activated state with features of both REM sleep and wakefulness. Although it is assumed that urethane produces unconsciousness, this has been questioned because of states of cortical activation during drug exposure. Furthermore, the similarities and differences between urethane anaesthesia and physiological sleep are still unclear. In this study, we recorded the electroencephalogram (EEG) and electromyogram in chronically prepared rats during natural sleep-wake states and during urethane anaesthesia. We subsequently analysed the power, coherence, directed connectivity and complexity of brain oscillations and found that EEG under urethane anaesthesia has clear signatures of unconsciousness, with similarities to other general anaesthetics. In addition, the EEG profile under urethane is different in comparison with natural sleep states. These results suggest that consciousness is disrupted during urethane. Furthermore, despite similarities that have led others to conclude that urethane is a model of sleep, the electrocortical traits of depressed and activated states during urethane anaesthesia differ from physiological sleep states.
氨基甲酸乙酯是一种广泛应用于动物研究的全身麻醉剂。氨基甲酸乙酯麻醉状态是独特的，因为它在宏观上明显不同的脑电图状态之间交替：一种类似于非快速眼动 (NREM) 睡眠的慢波状态和一种具有 REM 睡眠和觉醒特征的激活状态。尽管人们认为氨基甲酸乙酯会导致无意识，但由于在药物暴露期间存在皮质激活状态，这一点受到了质疑。此外，氨基甲酸乙酯麻醉和生理睡眠之间的相似之处和差异仍不清楚。在这项研究中，我们在慢性准备的大鼠中记录了自然睡眠-觉醒状态和氨基甲酸乙酯麻醉期间的脑电图 (EEG) 和肌电图。随后，我们分析了脑振荡的功率、相干性、有向连接和复杂性，发现氨基甲酸乙酯下的 EEG 具有明显的无意识特征，与其他全身麻醉剂相似。此外，与自然睡眠状态相比，氨基甲酸乙酯下的 EEG 模式也有所不同。这些结果表明，意识在氨基甲酸乙酯麻醉期间受到干扰。此外，尽管氨基甲酸乙酯已被认为是睡眠的模型，因为其具有相似性，但在氨基甲酸乙酯麻醉期间的抑制和激活状态的脑电图特征与生理睡眠状态不同。
