Research Service (151A3), Veterans Affairs Greater Los Angeles Healthcare System, 16111 Plummer Street, Sepulveda, Los Angeles, CA 91343, USA.
Department of Psychiatry, University of California, Los Angeles, CA 90095, USA.
Cells. 2022 Jul 7;11(14):2140. doi: 10.3390/cells11142140.
The ventrolateral preoptic area (VLPO) predominantly contains sleep-active neurons and is involved in sleep regulation. The perifornical-hypothalamic area (PF-HA) is a wake-regulatory region and predominantly contains wake-active neurons. VLPO GABAergic/galaninergic neurons project to the PF-HA. Previously, the specific contribution of VLPO neurons projecting to the PF-HA (VLPO > PF-HAPRJ) in sleep regulation in rats could not be investigated due to the lack of tools that could selectively target these neurons. We determined the contribution of VLPO > PF-HAPRJ neurons in sleep regulation by selectively activating them using designer receptors exclusively activated by designer drugs (DREADDs) in wild-type Fischer-344 rats. We used a combination of two viral vectors to retrogradely deliver the Cre-recombinase gene, specifically, in VLPO > PF-HA neurons, and further express hM3Dq in those neurons to selectively activate them for delineating their specific contributions to sleep−wake functions. Compared to the control, in DREADD rats, clozapine-N-oxide (CNO) significantly increased fos-expression, a marker of neuronal activation, in VLPO > PF-HAPRJ neurons (2% vs. 20%, p < 0.01) during the dark phase. CNO treatment also increased nonREM sleep (27% vs. 40%, p < 0.01) during the first 3 h of the dark phase, when rats are typically awake, and after exposure to the novel environment (55% vs. 65%; p < 0.01), which induces acute arousal during the light phase. These results support a hypothesis that VLPO > PF-HAPRJ neurons constitute a critical component of the hypothalamic sleep−wake regulatory circuitry and promote sleep by suppressing wake-active PF-HA neurons.
腹外侧视前区（VLPO）主要包含睡眠活性神经元，参与睡眠调节。穹窿周下丘脑区（PF-HA）是一个觉醒调节区域，主要包含觉醒活性神经元。VLPO GABAergic/galaninergic 神经元投射到 PF-HA。以前，由于缺乏能够选择性靶向这些神经元的工具，无法研究投射到 PF-HA 的 VLPO 神经元（VLPO > PF-HAPRJ）在大鼠睡眠调节中的特定贡献。我们通过在野生型 Fischer-344 大鼠中使用专门激活设计药物（DREADD）的设计受体选择性激活这些神经元，确定了 VLPO > PF-HAPRJ 神经元在睡眠调节中的贡献。我们使用两种病毒载体的组合，将 Cre 重组酶基因特异性递送到 VLPO > PF-HA 神经元中，然后在这些神经元中进一步表达 hM3Dq，以选择性激活它们，以描绘它们对睡眠-觉醒功能的特定贡献。与对照相比，在 DREADD 大鼠中，氯氮平-N-氧化物（CNO）在黑暗期显著增加了 VLPO > PF-HAPRJ 神经元中的 fos 表达（2%对 20%，p < 0.01），这是神经元激活的标志物。CNO 处理还增加了非快速动眼睡眠（27%对 40%，p < 0.01），在黑暗期的前 3 小时内，当大鼠通常清醒时，以及在暴露于新环境后（55%对 65%；p < 0.01），这会在光照期引起急性觉醒。这些结果支持了一个假设，即 VLPO > PF-HAPRJ 神经元构成了下丘脑睡眠-觉醒调节回路的一个关键组成部分，并通过抑制觉醒活性的 PF-HA 神经元来促进睡眠。
