Laboratory of Sleep Medicine and Chronobiology, Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC.
Ralph H. Johnson VA Medical Center, Charleston, SC.
Sleep. 2021 Jun 11;44(6). doi: 10.1093/sleep/zsaa268.
Sleep and wake are opposing behavioral states controlled by the activity of specific neurons that need to be located and mapped. To better understand how a waking brain falls asleep it is necessary to identify activity of individual phenotype-specific neurons, especially neurons that anticipate sleep onset. In freely behaving mice, we used microendoscopy to monitor calcium (Ca2+) fluorescence in individual hypothalamic neurons expressing the vesicular GABA transporter (vGAT), a validated marker of GABA neurons.
vGAT-Cre mice (male = 3; female = 2) transfected with rAAV-FLEX-GCaMP6M in the lateral hypothalamus were imaged 30 days later during multiple episodes of waking (W), non-rapid-eye movement sleep (NREMS) or REMS (REMS).
372 vGAT neurons were recorded in the zona incerta. 23.9% of the vGAT neurons showed maximal fluorescence during wake (classified as wake-max), 4% were NREM-max, 56.2% REM-max, 5.9% wake/REM max, while 9.9% were state-indifferent. In the NREM-max group, Ca2+ fluorescence began to increase before onset of NREM sleep, remained high throughout NREM sleep, and declined in REM sleep.
We found that 60.2% of the vGAT GABA neurons in the zona incerta had activity that was biased towards sleep (NREM and REMS). A subset of vGAT neurons (NREM-max) became active in advance of sleep onset and may induce sleep by inhibiting the activity of the arousal neurons. Abnormal activation of the NREM-max neurons may drive sleep attacks and hypersomnia.
睡眠和觉醒是由特定神经元活动控制的相反行为状态，需要对其进行定位和映射。为了更好地了解清醒大脑如何入睡，有必要识别特定表型神经元的个体活动，尤其是预测睡眠开始的神经元。在自由活动的小鼠中，我们使用微内窥镜监测表达囊泡 GABA 转运体 (vGAT) 的单个下丘脑神经元的钙 (Ca2+) 荧光，vGAT 是 GABA 神经元的有效标志物。
在 lateral hypothalamus 中转染 rAAV-FLEX-GCaMP6M 的 vGAT-Cre 小鼠（雄性=3；雌性=2），在多次清醒（W）、非快速眼动睡眠（NREMS）或快速眼动睡眠（REMS）期间进行成像。
在 zona incerta 中记录了 372 个 vGAT 神经元。23.9%的 vGAT 神经元在清醒时表现出最大荧光（归类为觉醒最大），4%为 NREM 最大，56.2%为 REM 最大，5.9%为觉醒/REM 最大，而 9.9%为状态无关。在 NREM 最大组中，Ca2+荧光在 NREM 睡眠开始前开始增加，在整个 NREM 睡眠期间保持较高水平，并在 REM 睡眠期间下降。
我们发现 zona incerta 中的 60.2%的 vGAT GABA 神经元的活动偏向于睡眠（NREM 和 REMS）。vGAT 神经元的一个亚群（NREM 最大）在睡眠开始前变得活跃，可能通过抑制觉醒神经元的活动来诱导睡眠。NREM 最大神经元的异常激活可能会导致睡眠发作和嗜睡症。
