Glial Control of CNS State-related Activity

描述（由申请人提供）：本项目研究腺苷水平的神经胶质控制及其在睡眠稳态中的作用。睡眠内稳态，即基于先前清醒时间的睡眠驱动，反映在长时间清醒后慢波活动增加（SWA，脑电图活动0.5-4.5 Hz振荡）和SWS后慢波活动减少。在人类、大鼠和小鼠的实验中都证实了在睡眠过程中SWA的消散和长时间清醒后SWA的积累。此外，SWA的积累和消散已经在野生型和突变型啮齿动物中建模，并且已知SWA的积累和消散受遗传控制。在当前的项目中，腺苷在SWA稳态中的作用被研究，首先通过基因敲除腺苷A1受体（AdoA1R），腺苷A1受体是腺苷影响SWA的主要腺苷受体，其次通过诱导敲除腺苷激酶（AdK），该激酶将腺苷转化为AMP，并且由于平衡转运体，在很大程度上控制了腺苷的细胞外水平。腺苷激酶主要在成年动物的神经胶质中表达，因此，如果腺苷影响SWA的内稳态，正如我们假设的那样，这将证明神经胶质控制SWA的内稳态。该项目有3个具体目标：1)表征AdoA1Rs在基线条件下SWA积累和消散以及睡眠剥夺条件下恢复中的作用；2)表征胶质AdK在AdoA1R介导的哺乳动物皮质神经元抑制tone中的作用；3)表征胶质AdK在基线条件下SWA积累和消散以及睡眠剥夺条件下恢复中的作用。总的来说，这些特定的目的是研究一种潜在的神经生物学底物，腺苷，它可能影响睡眠驱动的SWA积累和消散。众所周知，腺苷会影响SWA，因此将这种化合物作为控制SWA稳态的神经生物学底物进行测试是合理的。初步数据支持AdoA1R在SWA内稳态中的作用，并提示胶质介导的AdK敲除增加腺苷水平，也会改变SWA内稳态，但方向与AdoA1R敲除相反。这些发现将为神经胶质控制行为状态相关的SWA提供一种对神经胶质代谢状态敏感的机制。

DESCRIPTION (provided by applicant): This project investigates glial control of adenosine levels and its role in sleep homeostasis. Sleep homeostasis, the drive to sleep based on prior waking time, is reflected by increased slow wave activity (SWA, 0.5-4.5 Hz oscillation in electroencephalographic activity) following prolonged waking and decreased SWA following SWS. This dissipation in SWA during SWS and buildup of SWA following prolonged waking has been demonstrated in humans, rats, and mice. Further, SWA accumulation and dissipation has been modeled in wildtype and mutant rodents and it is known that SWA accumulation and dissipation is under genetic control. In the current project, the role of adenosine in SWA homeostasis is investigated, first by using a genetic knockout of adenosine A1 receptors (AdoA1R), the main adenosine receptor through which adenosine influences SWA, and secondly by using an inducible knockout of adenosine kinase (AdK), which converts adenosine to AMP and, due to equilibrative transporters, largely controls the extracellular level of adenosine. Adenosine kinase is expressed primarily in glia in adult animals and therefore, if adenosine influences SWA homeostasis, as we hypothesize it does, this would demonstrate glial control of SWA homeostasis. The project uses 3 specific aims to: 1) characterize the role of AdoA1Rs in SWA accumulation and dissipation under baseline and recovery from sleep deprivation conditions, 2) characterize the role of glial AdK in AdoA1R mediated inhibitory tone on mammalian cortical neurons, and 3) characterize the role of glial AdK in accumulation and dissipation of SWA under baseline and recovery from sleep deprivation conditions. Overall, these specific aims investigate one potential neurobiological substrate, adenosine, which may influence the SWA accumulation and dissipation that is indicative of the sleep drive. Adenosine is known to influence SWA so it is reasonable to test this compound as a neurobiological substrate that controls SWA homeostasis. Preliminary data support a role of AdoA1R in SWA homeostasis and suggest glial-mediated AdK knockout, which increases adenosine levels, also alters SWA homeostasis but in the opposite direction as AdoA1R knockout. These findings will provide a mechanism for glial control of behavioral state related SWA that is sensitive to glial metabolic state. PUBLIC HEALTH RELEVANCE: Sleep is an important and necessary behavior; however, control of sleep drive in response to sleep loss, is not well understood. This project investigates a possible mechanism for this control mediated by brain adenosine. Further, the control of this adenosine by adenosine kinase in glia (non-neuronal supporting cells) will be characterized.