Neurotransmitter modulation of neurogenesis in the adult enteric nervous system

成人肠神经系统神经发生的神经递质调节

• 批准号: RGPIN-2014-06259
• 负责人: Lomax, Alan
• 金额: $ 2.55万
• 依托单位: Queen's University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=588904
• 关键词: Neurotransmitter; modulation; neurogenesis; adult; enteric

The enteric nervous system (ENS), embedded within the wall of the gut, contains nerve circuits that can modulate gut function in the absence of any connections to the central nervous system. Enteric neurons have adapted to survive the hostile environment of the gut, where large distending boluses of food and the likelihood of infection and inflammation can impact the ENS. Enteric neurons are capable of impressive plasticity of form and function, including long-lasting changes in synaptic transmission, neuronal morphology and neurochemistry. Importantly, a population of neural precursor cells (NPCs or stem cells) has recently been identified within the adult ENS. These cells are a subset of enteric glia and are capable of generating new enteric neurons and glial cells in vitro. Enteric neurogenesis has also been demonstrated in vivo, although neurogenesis occurs more readily in vitro. Unfortunately, the signaling pathways that modulate the proliferation and differentiation of enteric NPCs are currently unknown. During embryonic development, the proliferation, migration and differentiation of enteric NPCs are subject to modulation by enteric neurotransmitters. We hypothesised that the proliferation and differentiation of adult enteric NPCs in vivo are suppressed by enteric neurotransmission, and that removal of this inhibitory influence during in vitro dissociated culture promotes neurogenesis. Our preliminary data strongly support this hypothesis. Therefore, we will study the effects of drugs that manipulate enteric neurotransmission on enteric neurogenesis. We will examine how neurotransmitters modulate two fundamental processes in neurogenesis: i) proliferation of NPCs and ii) their differentiation to mature neurons. Acetylcholine, noradrenaline, ATP, serotonin and substance P will be examined, due to their roles as enteric neurotransmitters and evidence for enteric glial expression of receptors for these neurotransmitters. Using primary cultures of dissociated myenteric neurons and glia, which lack synaptic transmission, and organotypic cultures of intact myenteric plexus, which retain functional synapses, we will address the following aims: Aim 1. Identify which neurotransmitters and receptors modulate enteric NPC proliferation. Immunohistochemical experiments and labeling of proliferating cells will be employed to determine the effects of neurotransmission of enteric NPC proliferation. Aim 2. Determine whether enteric neurotransmitters modify the differentiation of enteric NPCs into mature enteric neurons. We will utilize electrophysiological recordings and quantification of the neurochemical classes of enteric neurons to characterise the effects of enteric neurotransmitters on neuronal differentiation. The proportion of glial cells and neurons formed in vitro will also be compared to the proportions formed during embryonic development. In addition to providing superb training for highly qualified individuals, these experiments could re-define the roles of neurotransmission in the ENS. These data are also likely to improve our understanding of how enteric neurons have adapted to the relatively hostile environment of the gut. Our findings may ultimately lead to a paradigm shift in how neural stem cells can be manipulated in vivo.

肠神经系统（ENS），嵌入肠壁内，包含神经回路，可以在没有任何连接到中枢神经系统的情况下调节肠道功能。 肠神经元已经适应了在肠道的恶劣环境中生存，其中大的膨胀的食物团以及感染和炎症的可能性可以影响ENS。肠神经元能够具有令人印象深刻的形式和功能的可塑性，包括突触传递、神经元形态和神经化学的持久变化。重要的是，神经前体细胞（NPC或干细胞）的人口最近已被确定在成人ENS。这些细胞是肠神经胶质细胞的一个子集，并能够产生新的肠神经元和神经胶质细胞在体外。 肠神经发生也已在体内得到证实，尽管神经发生在体外更容易发生。 不幸的是，目前尚不清楚调节肠道NPC增殖和分化的信号传导途径。 在胚胎发育过程中，肠道NPC的增殖、迁移和分化受到肠道神经递质的调节。 我们假设，成人肠道NPC在体内的增殖和分化受到肠道神经传递的抑制，并在体外分离培养过程中消除这种抑制性影响，促进神经发生。 我们的初步数据强烈支持这一假设。 因此，我们将研究操纵肠神经传递的药物对肠神经发生的影响。 我们将研究神经递质如何调节神经发生中的两个基本过程：i）NPC的增殖和ii）它们向成熟神经元的分化。 由于乙酰胆碱、去甲肾上腺素、ATP、5-羟色胺和P物质作为肠道神经递质的作用以及这些神经递质受体在肠神经胶质表达的证据，将对它们进行检查。使用分离的肌间神经元和神经胶质细胞的原代培养物（缺乏突触传递）和完整的肌间神经丛的器官型培养物（保留功能性突触），我们将解决以下目标： 目标1. 确定哪些神经递质和受体调节肠道NPC增殖。 免疫组化实验和增殖细胞的标记将被用来确定神经传递的肠NPC增殖的影响。 目标2. 确定肠神经递质是否改变肠NPC分化为成熟的肠神经元。我们将利用电生理记录和定量的肠神经元的神经化学类来验证肠神经递质对神经元分化的影响。 还将体外形成的神经胶质细胞和神经元的比例与胚胎发育期间形成的比例进行比较。 除了为高素质的个体提供极好的训练外，这些实验还可以重新定义神经传递在ENS中的作用。这些数据也可能提高我们对肠神经元如何适应肠道相对恶劣环境的理解。 我们的发现可能最终导致神经干细胞在体内如何操作的范式转变。