The Role of Neurotensin-Expressing Neurons of the Extended Ventrolateral Preoptic Nucleus in REM Sleep Regulation

项目摘要/摘要 睡眠是一个活跃的过程，需要睡眠促进细胞的分界节点参与 人口。过去二十年的研究表明，甘丙素表达的神经元在 视前外侧核(VLPOGal)是正常睡眠所必需的。而部分VLPO甘丙素 神经元集中在一个簇中，即所谓的VLPO核心(CVLPO)，其他神经元散布在背部和 在该核心的中间，一个区域后来被称为扩展VLPO(EVLPO)。损伤与光遗传 研究表明，cVLPO和eVLPO中的甘丙素表达神经元有两种。 具有非快速眼动睡眠(NREM)所需cVLPOGal神经元的功能不同的细胞群，而 快速眼动睡眠所需的eVLPOGal神经元。解剖示踪研究表明，eVLPOGal神经元 支配与快速眼动睡眠调节有关的脑干核团，通过这些下行投射， EVLPOGal神经元被认为通过解除对REM产生的神经元的抑制来促进REM睡眠 脑桥网状结构。然而，在我们对这一问题的理解上仍然存在几个根本的差距 EVLPOGal神经元驱动REM睡眠的细胞和突触基础。研究eVLPOGal种群 已经被证明是相当具有挑战性的，因为cVLPO和eVLPO是距离很近的小区域 接近，到目前为止，还没有选择性靶向的标记。我们最近发现了一个潜在的 EVLPOGal神经元的标记，它将允许我们独立于 它们邻近的cVLPOGal神经元。具体来说，我们发现：1)eVLPOGal神经元选择性地 神经降压素的表达和，2)对神经降压素eVLPO神经元的化学生成抑制 减少快速眼动睡眠。我们还发现，eVLPO神经降压素神经元将强大的投射发送到区域 已知可抑制快速眼动睡眠的中脑和脑桥，包括中脑导水管周围腹外侧区 灰质(VlPAG)和蓝斑(LC)。在这些结果的基础上，我们建议eVLPO 神经降压素神经元通过抑制脑桥网状结构中的REM生成神经元促进REM睡眠 通过抑制vlPAG的GABA神经元和LC的单胺能神经元而形成。海流 因此，该提议试图首先在体外，然后在体内，确定脑干传出输出，通过它 EVLPO神经降压素神经元驱动REM睡眠。为此，我们将首先在特定的目标1中使用体外电路 标测以确定eVLPO神经降压素神经元靶向的突触后神经元。具体而言 目的2，我们将使用体内光遗传学来测试在体外研究中首次发现的电路是否 足以产生快速眼动睡眠。鉴于这项提议试图填补的巨大知识缺口，我们预计会有结果 为eVLPO神经降压素的进一步研究提供了一个重要的解释框架 促进快速眼动睡眠的必要和充分的途径，以及2)更广泛地说，对 视前区在快速眼动睡眠调节中的作用。

Project Summary/Abstract Sleep is an active process requiring the participation of delimited nodes of sleep-promoting cell populations. Work over the last twenty years has demonstrated that galanin expressing neurons in the ventrolateral preoptic (VLPOGal) nucleus are necessary for normal sleep. While a portion of VLPO galanin neurons is concentrated in a cluster, the so-called VLPO core (cVLPO), others are scattered dorsally and medially to that core, a region that came to be known as the extended VLPO (eVLPO). Lesion and optogenetic studies have demonstrated that the galanin expressing neurons in the cVLPO and those in the eVLPO are two functionally distinct cell groups with the cVLPOGal neurons required for non-REM sleep (NREM) while the eVLPOGal neurons required for REM sleep. Anatomical tracing studies have shown that the eVLPOGal neurons innervate brainstem nuclei implicated in REM sleep regulation and through these descending projections, the eVLPOGal neurons are thought to promote REM sleep by the disinhibition of the REM-generating neurons in the pontine reticular formation. There remain however several fundamental gaps in our understanding of the cellular and synaptic basis by which eVLPOGal neurons drive REM sleep. Studying the eVLPOGal population has been proven to be quite challenging as the cVLPO and the eVLPO are small regions located in close proximity and until now, there were no markers for selective targeting. We have recently discovered a potential marker for the eVLPOGal neurons that will allow us to manipulate the eVLPOGal neurons independently from their neighboring cVLPOGal neurons. Specifically, we have found that: 1) the eVLPOGal neurons selectively express the neuropeptide neurotensin and, 2) that chemogenetic inhibition of the neurotensin eVLPO neurons reduces REM sleep. We have also found that eVLPO neurotensin neurons send robust projections to regions of the midbrain and pons that are known to suppress REM sleep including the ventrolateral periaqueductal gray (vlPAG) and the locus coeruleus (LC). On the basis of these results, we propose that the eVLPO neurotensin neurons promote REM sleep by disinhibiting REM-generating neurons in the pontine reticular formation via inhibition of GABA neurons of the vlPAG and monoaminergic neurons of the LC. The current proposal thus seeks to identify, first in vitro and then in vivo, the brainstem efferent outputs through which the eVLPO neurotensin neurons drive REM sleep. To do so, we will first employ, in Specific Aims 1, in vitro circuit mapping to identify the postsynaptic neurons that are targeted by the eVLPO neurotensin neurons. In Specific Aim 2, we will use in vivo optogenetics to test whether the circuits first identified in the in vitro studies are sufficient to produce REM sleep. Given the large knowledge gap this proposal seeks to fill, we expect results from this work to provide 1) an important interpretative framework for future studies on the eVLPO neurotensin pathways that are necessary and sufficient for promoting REM sleep and 2) more generally, a novel insight into the role of the preoptic region in REM sleep regulation.