Mechanisms underlying the effects of retinoic acid on neurite outgrowth and network plasticity

视黄酸对神经突生长和网络可塑性影响的机制

• 批准号: RGPIN-2015-03780
• 负责人: Spencer, Gaynor
• 金额: $ 3.28万
• 依托单位: Brock University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=612566
• 关键词: Mechanisms; underlying; effects; retinoic; acid

The main aim of my research program is to study the effects of the essential Vitamin A metabolite, retinoic acid, on nervous system function. Retinoic acid is important for nervous system development and regeneration, as well as for learning and memory in the adult brain. We study these aspects of retinoid signaling using the central nervous system (CNS) of the mollusc, Lymnaea stagnalis. Unlike most vertebrate species, molluscan adult CNS neurons can regenerate. Growth cones, which are located at the tips of growing nerve fibres (neurites) play an important role in axon guidance during development and regeneration. In Lymnaea, growth cones of cultured regenerating CNS neurons are large and robust and we have shown that they respond to and turn toward a focal source of retinoic acid, which we hypothesize is acting as an important guidance molecule during development and regeneration. It is known that many guidance molecules are well conserved across vertebrate and invertebrate species, so Lymnaea neurons are ideal for investigating the cellular and molecular mechanisms underlying retinoic acid-induced growth cone turning, which are currently largely unknown. Over the next grant cycle, we will  investigate the role of retinoid receptors and potential downstream second messengers in the growth cone turning response to retinoic acid. Recently, we have also discovered an extremely novel "floating growth cone" phenomenon, where regenerating neurites from the cut nerves of a dissected Lymnaea CNS, grow along the air-water interface. As substrate-adhesion is normally required for neurite outgrowth and regeneration, this is a novel regenerating event which will be used to provide novel insights into growth cone behaviour that can not easily be addressed in cell culture or in the intact animal. Another advantage of using Lymnaea is that many neurons located on the surface of its CNS are individually identifiable, with known transmitters, synaptic partners and functions. We can culture and/or electrically record from single identifiable neurons involved in a specific behavior, such as feeding or respiration. Furthermore, these behaviours can be modified by training, and animals demonstrate both learning and memory.  We have shown that inhibiting retinoic acid signaling in Lymnaea prevents long-term memory formation, and we are now studying the cellular and network properties affected by this essential signaling molecule. To this end, we can study single identified neurons or synapses in cell culture, but also study these same identified neurons embedded in their neuronal networks in the intact isolated CNS, or a behaving “semi-intact” preparation, in which we can simultaneously monitor behavior and neuronal activity. These studies provide us with a unique opportunity to investigate retinoid functioning in memory formation and the underlying network changes, using a relatively simple nervous system.

我的研究项目的主要目的是研究必需的维生素 A 代谢物视黄酸对神经系统功能的影响。视黄酸对于神经系统的发育和再生以及成人大脑的学习和记忆非常重要。我们利用软体动物（Lymnaea stagnalis）的中枢神经系统（CNS）来研究类维生素A信号传导的这些方面，与大多数脊椎动物不同，软体动物的成年中枢神经系统神经元可以再生。位于生长神经纤维（神经突）尖端的视锥细胞在发育和再生过程中在轴突引导中发挥着重要作用。转向视黄酸的焦点来源，我们所追求的视黄酸在发育和再生过程中充当重要的指导分子众所周知，许多指导分子在脊椎动物和无脊椎动物物种中都非常保守。 Lymnaea 神经元是研究视黄酸诱导生长锥转动的细胞和分子机制的理想选择，目前尚不清楚。在下一个资助周期中，我们将研究类维生素A受体和潜在的下游第二信使在生长锥转动中的作用。对视黄酸的反应。 最近，我们还发现了一种极其新颖的“浮动生长锥”现象，其中解剖的 Lymnaea CNS 神经的再生神经突沿着空气-水界面生长，因为神经突的生长和再生通常需要基质粘附，这是一个新颖的再生事件，将用于提供对生长锥行为的新见解，而这些行为在细胞培养物或完整动物中不容易解决。 使用 Lymnaea 的另一个优点是，位于中枢神经系统表面的许多神经元都是可单独识别的，具有已知的递质、突触伙伴和功能，我们可以对参与特定行为（例如进食）的单个可识别神经元进行培养和/或电记录。此外，这些行为可以通过训练来改变，并且动物表现出学习和记忆能力。我们已经证明，抑制 Lymnaea 中的视黄酸信号可以阻止长期记忆的形成，我们现在正在研究细胞和网络特性。为此，我们可以研究细胞培养物中单个已识别的神经元或突触，也可以研究嵌入在完整分离的中枢神经系统或行为“半完整”制剂中的神经网络中的相同已识别神经元。 ，我们可以同时监测行为和神经活动，这些研究为我们提供了一个独特的机会，可以使用相对简单的神经系统来研究类维生素A在记忆形成中的功能和潜在的网络变化。