Neurotransmitter Roles During Neurogenesis

神经递质在神经发生过程中的作用

基本信息

批准号：
6502143
负责人：
JEFFERY BARKER
金额：
--
依托单位：
NATIONAL INSTITUTE OF NEUROLOGICAL DISORDERS AND STROKE
依托单位国家：
美国
项目类别：
财政年份：
资助国家：
美国
起止时间：
至
项目状态：
未结题

项目摘要

Summary of Work: The physiological mechanisms associated with neurogenesis and gliogenesis in the embryonic mammalian CNS have become an area of increasing study. Here, they are being studied using a novel strategy combining surface phenotyping with flow cytometry to access directly the physiological properties emerging during neuronal and glial cell lineage progression. Evidence has accumulated that neurotransmitters like acetylcholine (ACh) and GABA appear during neurogenesis where they are thought to play key roles in this process. During FY2001 neural stem cells and neuronal and glial progenitors were isolated from the embryonic cortex by phenotyping and flow cytometry. Stem cells either self-renewed or differentiated into neurons or glia depending on specific growth factors added to the culture. Clonal analysis showed that over time in culture cells underwent self-regulated lineage progression in the undisturbed microenvironment. Proliferating precursors were contiguous with proliferating progenitors, which were arrayed adjacent to differentiating neurons, astrocytes or oligodendrocytes depending on the lineage. This shows that in vitro all of the developmental signals necessary to generate the different stages of neuronal and glial lineages are conveyed in the microenvironment among the cells. Physiological properties and specific growth factor and neurotransmitter receptor and ion channel functions emerging de novo during cell lineage progression recapitulated those appearing in vivo. Growth factor-mediated Ca2+ signalling and self-renewal both involved several interactive pathways. ACh regulated neuronal progenitor cell but not stem cell proliferation via several muscarinic receptors both in vitro and in vivo. Pharmacological block of cholinergic signaling at muscarinic receptors prevented cells from re-entering the cell-cycle and synthesizing DNA. Instead, the cells underwent apoptosis and died. Thus, ACh plays a key role in cortical progenitor cell expansion. Other research has shown that GABA mediates mitogenic, motogenic and morphogenic roles during cortical neurogenesis. GABA stimulated 1) progenitor cell proliferation acting via GABA(A) receptors, 2) postmitotic neuron migration via GABA(B) and 3) neurite outgrowth of postmigratory cortical neurons via GABA(A) receptors. ACh did not share these latter roles. The morphogenic effects of GABA resulted from constitutive synthesis, transport and release from a surface-accessible compartment. This morphogenic role of GABA disappeared following neurite outgrowth and the formation of functional synapses. In summary, the results show that in the rat two widely distributed neurotransmitters play important mitogenic and/or motogenic and morphogenic roles during neurogenesis before they mediate brief synaptic signals.

工作摘要：胚胎哺乳动物中枢神经系统中与神经发生和神经胶质发生相关的生理机制已成为越来越多的研究领域。在这里，他们正在使用一种新型策略与流式细胞术结合表面表型的新策略，以直接访问神经元和神经胶质细胞谱系过程中出现的生理特性。有证据表明，在神经发生过程中，乙酰胆碱（ACH）和GABA等神经递质被认为在此过程中起关键作用。在2001财年期间，神经干细胞以及神经元和神经胶质祖细胞通过表型和流式细胞仪从胚胎皮层中分离出来。干细胞自我更新或分化为神经元或神经胶质，具体取决于添加到培养物中的特定生长因子。克隆分析表明，随着时间的流逝，培养细胞在不受干扰的微环境中经历了自调节的谱系进展。增殖前体与增生的祖细胞相邻，这些祖细胞与分化神经元，星形胶质细胞或少突胶质细胞相邻，具体取决于谱系。这表明，在体外，在细胞之间的微环境中传达了产生神经元和神经胶质谱系不同阶段所需的所有发育信号。在细胞谱系进展过程中，生理特性和特异性生长因子以及神经递质受体和离子通道功能概括了在体内出现的人。生长因子介导的Ca2+信号传导和自我更新都涉及几种互动途径。 ACH调节神经元祖细胞，而不是通过体外和体内的几种毒蕈碱受体进行干细胞增殖。毒蕈碱受体胆碱能信号传导的药理阻滞阻止细胞重新进入细胞周期和合成DNA。相反，细胞经过凋亡并死亡。因此，ACH在皮质祖细胞膨胀中起关键作用。其他研究表明，GABA在皮质神经发生过程中介导有丝分裂，动作和形态发生作用。 GABA刺激了1）通过GABA受体作用的祖细胞增殖（2）通过GABA（b）和3）通过GABA（a）受体的迁移皮质神经元的神经突生长（b）和3）神经突生长。 ACH没有分享这些后者的角色。 GABA的形态学作用是由构成性的合成，运输和释放的，该隔室的运输和释放。 GABA的这种形态发生作用在神经突产物和功能突触的形成后消失。总而言之，结果表明，在大鼠中，两个分布的神经递质在神经发生过程中起着重要的有丝分裂和/或运动和形态发挥作用，然后它们介导了短暂的突触信号。