Identifying the Role of Serotonergic Signaling in the Maturation ofDendritic Spines

项目总结 大脑功能发育需要神经化学物质的精确协调，使神经元能够 形成突触并相互交流。发育关键时期的突触不成熟 时间窗通常会导致认知障碍，例如在自闭症谱系障碍中观察到的那些，这可能 坚持到成年。在人类和啮齿动物身上的研究表明，5-羟色胺(5-HT)在 出生前和出生后早期发育到行为和认知障碍和不规则的比率增加 神经元发育。前额叶皮质(PFC)是大脑中在信息处理中起关键作用的一个区域 当5-羟色胺水平改变时，高级认知功能被扰乱。在早期的PFC开发中， 回路的形成依赖于兴奋性突触的功能成熟和稳定，位于 树枝状刺。我们的初步研究确定了5-羟色胺在树突棘发育中的关键作用 在PFC内，表明脊柱密度和大小在操纵5-羟色胺水平后直接改变 出生后早期。这一提议由两个目标组成，旨在检验5-羟色胺可以 在单一突触水平上增强和稳定树突棘。第一个目标使用了多种技术的组合 包括双色、双光子照射5-羟色胺和谷氨酸神经递质、电生理学、 光遗传学和药理学来确定5-羟色胺是否可以诱导功能性的长时程增强 单独的树枝状刺。第二个目标是确定内源性5-羟色胺信号是否可以 稳定新生的树突棘，这将通过光遗传学、双光子5-羟色胺去势来研究 以及包括药理学方法和荧光寿命成像在内的机制研究。一起， 这些研究试图确定5-羟色胺依赖的信号在突触成熟和稳定中的作用。 细胞和分子水平。该项目的结果将是更好地缓解 由于发育中的大脑早期5-羟色胺失衡而导致的认知障碍。

PROJECT SUMMARY Functional brain development requires the precise coordination of neurochemicals that allow neurons to form synapses and communicate with one another. Improper synaptic maturation during critical developmental time windows often lead to cognitive disabilities, such as those observed in autism spectrum disorders, that can persist into adulthood. Studies in humans and rodents have linked disbalances of serotonin (5-HT) during prenatal and early postnatal development to increased rates of behavioral and cognitive deficits and irregular neuronal development. The prefrontal cortex (PFC) is a region of the brain that plays a key role in processing higher order cognitive functions that are disrupted when 5-HT levels are altered. During early PFC development, circuit formation is dependent on the functional maturation and stabilization of excitatory synapses, located on dendritic spines. Our preliminary studies identified a critical role for 5-HT in the development of dendritic spines within the PFC, indicating that both spine density and size are directly altered after manipulating 5-HT levels in early postnatal periods. This proposal is comprised of two aims which seek to test the hypothesis that 5-HT can potentiate and stabilize dendritic spines at a single synapse level. The first aim uses a combination of techniques including two-color, two-photon uncaging of 5-HT and glutamate neurotransmitters, electrophysiology, optogenetics, and pharmacology to determine whether 5-HT can induce functional long-term potentiation of individual dendritic spines. The second aim is designed to identify whether endogenous 5-HT signaling can stabilize nascent dendritic spines, which will be investigated by using optogenetics, two-photon 5-HT uncaging and mechanistic studies that include pharmacological approaches and fluorescence lifetime imaging. Together, these studies seek to establish the role of 5-HT dependent signaling in synapse maturation and stabilization at a cellular and molecular level. Results from this project will be essential knowledge towards better mitigating the cognitive disabilities that result from early 5-HT disbalances in the developing brain.