Dissecting Mechanisms of Striatal Acetylcholine Transmission in the Vertebrate Brain

项目总结 乙酰胆碱通过对大脑回路的调节，关键地控制着复杂的神经功能。在……里面 与神经肌肉接头上乙酰胆碱信号转导机制的研究不同，其 脊椎动物中枢神经系统的传播模式和机制还不是很清楚。在 在纹状体，乙酰胆碱对局部多巴胺能活动具有快速而强大的控制作用。加在一起，这些 神经调节剂调节各种重要的行为，包括动机和与奖励相关的学习。 由于乙酰胆碱在纹状体组织中释放后会迅速降解，因此乙酰胆碱对 多巴胺信号必须涉及释放部位和受体之间的紧密空间关系，和/或 传输速度快。然而，神经调节剂信号被经典地模拟为通过音量发生 传递，涉及分散的、非特异性的释放，而不是突触的、点对点的信号-a 这个概念还有待验证。此外，纹状体乙酰胆碱的分子机制 信号仍然难以捉摸。我假设稀疏的胆碱能终末需要分子元素才能高度 同步释放乙酰胆碱。在这种情况下，快速和精确的囊泡释放可能会产生 高浓度乙酰胆碱的同步波，这可能允许甚至遥远的受体感觉到这一点 发出强有力的信号。 为了验证这一假设，我建议检查纹状体的形态和分子底物。 乙酰胆碱在两个目标中的传递。首先，我将剖析乙酰胆碱到多巴胺信号的结构。 在纹状体，包括乙酰胆碱神经末梢和它们的分泌机械的存在 用超分辨显微镜观察多巴胺轴突上的乙酰胆碱受体。在第二个目标中，我 将从功能上测试乙酰胆碱释放到多巴胺轴突上是否需要分泌蛋白质 注定会产生快速和精确的释放，使乙酰胆碱能够相性传输。另外，我会 确定这种传输模式如何影响后续的多巴胺信号。为此，我将使用Genetic 与荧光乙酰胆碱传感器和安培多巴胺同时成像的工具 以纹状体切片为单位进行测量。综上所述，这些发现将有助于我们对 纹状体中的胆碱能到多巴胺能信号，包括识别重要的基因 调节乙酰胆碱的传递。这种分子水平的理解最终将对更好地 了解大脑功能和疾病。

PROJECT SUMMARY Acetylcholine critically controls complex neurological functions through its modulation of brain circuits. In contrast to the well-studied mechanisms of acetylcholine signaling at the neuromuscular junction, its transmission modes and mechanisms in the vertebrate central nervous system are not well understood. In the striatum, acetylcholine exerts rapid and powerful control over local dopaminergic activity. Together, these neuromodulators regulate a variety of important behaviors, including motivation and reward-related learning. Because acetylcholine is rapidly degraded after it is released in striatal tissues, the fidelity of acetylcholine to dopamine signaling must involve either tight spatial relationships between release sites and receptors, and/or fast transmission. However, neuromodulator signaling is classically modeled as occurring through volume transmission, involving dispersed, non-specific release as opposed to synaptic, point-to-point signaling – a concept that remains to be proven. Furthermore, the molecular mechanisms underlying striatal acetylcholine signaling remain elusive. I hypothesize that sparse cholinergic terminals require molecular elements for highly synchronous acetylcholine release. In this scenario, rapid and precise vesicle release could produce a synchronous wave of high-concentration acetylcholine, which might allow even distant receptors to sense this signal with potency. To test this hypothesis, I propose to examine the morphological and molecular substrate of striatal acetylcholine transmission in two aims. First, I will dissect the structure of acetylcholine to dopamine signaling in the striatum, including the presence of secretory machinery in acetylcholine nerve terminals and their apposition to acetylcholine receptors on dopamine axons, using superresolution microscopy. In a second aim, I will functionally test whether acetylcholine release onto dopamine axons requires secretory proteins that are predestined to generate fast and precise release, enabling phasic acetylcholine transmission. Additionally, I will determine how this transmission mode impacts subsequent dopamine signaling. To do this, I will use genetic tools paired with simultaneous imaging of fluorescent acetylcholine sensors and amperometric dopamine measurements in striatal slices. Together, these findings will inform our fundamental understanding of cholinergic to dopaminergic signaling in the striatum, including the identification of important genes that regulate acetylcholine transmission. This molecular-level understanding will ultimately be important to better understand brain function and disease.