Lapierre Jennifer L, Kosenko Peter O, Lyamin Oleg I, Kodama Tohru, Mukhametov Lev M, Siegel Jerome M
Department of Psychiatry, School of Medicine, University of California Los Angeles and Neurobiology Research, Veterans Affairs Greater Los Angeles Healthcare System, North Hills, California 91343, USA.
J Neurosci. 2007 Oct 31;27(44):11999-2006. doi: 10.1523/JNEUROSCI.2968-07.2007.
Fur seals are unique in that they display both bilateral slow-wave sleep (BSWS), as seen in all terrestrial mammals, and slow-wave sleep with interhemispheric electroencephalogram (EEG) asymmetry, resembling the unihemispheric slow waves of cetaceans. Little is known about the underlying mechanisms of this phenomenon, which is also termed asymmetrical slow wave sleep (ASWS). However, we may begin to understand the expression of ASWS by studying the neurotransmitter systems thought to be involved in the generation and maintenance of sleep-wake states in terrestrial mammals. We examined bilaterally the release of cortical acetylcholine (ACh), a neurotransmitter implicated in the regulation of cortical EEG and behavioral arousal, across the sleep-wake cycle in four juvenile northern fur seals (Callorhinus ursinus). In vivo microdialysis and high-performance liquid chromatography coupled with electrochemical detection were used to measure cortical ACh levels during polygraphically defined behavioral states. Cortical ACh release was state-dependent, showing maximal release during active waking (AW), similar levels during quiet waking (QW), and rapid eye movement (REM) sleep, and minimal release during BSWS. When compared with BSWS, cortical ACh levels increased approximately 300% during AW, and approximately 200% during QW and REM sleep. During these bilaterally symmetrical EEG states, ACh was synchronously released from both hemispheres. However, during ASWS, ACh release was lateralized with greater release in the hemisphere displaying lower voltage activity, at levels approximating those seen in QW. These findings demonstrate that cortical ACh release is tightly linked to hemispheric EEG activation.
海狗很独特，因为它们既表现出所有陆生哺乳动物都有的双侧慢波睡眠（BSWS），也表现出伴有半球间脑电图（EEG）不对称的慢波睡眠，类似于鲸类动物的单侧慢波。对于这种也被称为不对称慢波睡眠（ASWS）现象的潜在机制知之甚少。然而，通过研究被认为参与陆生哺乳动物睡眠 - 觉醒状态产生和维持的神经递质系统，我们或许可以开始理解ASWS的表现。我们双侧检测了四只幼年北海狗（Callorhinus ursinus）在睡眠 - 觉醒周期中皮质乙酰胆碱（ACh）的释放情况，ACh是一种与皮质脑电图调节和行为觉醒有关的神经递质。采用体内微透析和高效液相色谱结合电化学检测技术，在多导仪定义的行为状态下测量皮质ACh水平。皮质ACh释放取决于行为状态，在主动觉醒（AW）期间释放量最大，在安静觉醒（QW）和快速眼动（REM）睡眠期间水平相似，而在BSWS期间释放量最小。与BSWS相比，皮质ACh水平在AW期间增加约300%，在QW和REM睡眠期间增加约200%。在这些双侧对称的脑电图状态下，ACh从两个半球同步释放。然而，在ASWS期间，ACh释放发生偏侧化，在显示较低电压活动的半球释放量更大，其水平接近QW时的水平。这些发现表明皮质ACh释放与半球脑电图激活紧密相关。
