Collaborative Research: Molecular Mechanisms of Astrocyte Neuron Interactions in the Development of Synchronous Activity in Neuronal Networks

脑细胞有两种类型。神经元是最著名的；它们通过产生电活动尖峰来相互交流。第二种细胞是神经胶质细胞，它扮演着各种各样的角色，但人们对它的了解却很少。在清醒的成年人大脑中，神经元的整体尖峰活动似乎是随机的。然而，在深度睡眠或麻醉下，尖峰活动模式在大脑不同区域内部和之间变得同步。在大脑发育过程中，这种类型的同步尖峰被认为是电路成熟以及大脑功能组织的建立和维持所必需的。本研究的重点是了解一种胶质细胞（星形胶质细胞）在发育中的大脑中同步尖峰活动模式的出现中的作用。主要的假设是星形胶质细胞在大脑神经元活动的同步中起决定性作用。初步数据表明，星形胶质细胞是同步尖峰活动所必需的；提出的研究将阐明星形胶质细胞内控制周围神经元尖峰同步的分子途径。这项研究的结果将确定星形细胞-神经元相互作用的基本机制，在大脑发育过程中形成同步活动。该项目在一所历史悠久的黑人大学进行，将让少数族裔学生沉浸在前沿神经科学研究中，并在本科生和研究生研究人员之间的互动基础上促进同伴指导。在多电极阵列（MEAs）上使用混合神经元和星形胶质细胞培养的初步数据显示，与不含星形胶质细胞的神经元培养相比，随机峰活动随着时间的推移而同步，而星形胶质细胞培养只显示随机活动而不同步。本研究的主要假设是mGluR1 g蛋白偶联受体（GPCR）通路介导的星形胶质细胞谷氨酸释放介导了星形胶质细胞对神经元同步活动发育的影响。星形胶质细胞mGluR1通路介导神经元同步的机制模型将使用几种不同的显性负构式进行测试。一个阻断下游信号传导的显性阴性mGluR1受体将用于理解该信号通路在群体同步中的作用，以及星形胶质细胞内钙振荡与神经元同步爆发发展之间的时间关系。一个显性阴性的SNARE蛋白Vamp2/Syb2将用于阻断星形胶质细胞的谷氨酸释放。mGluR1通路和mGluR1介导的谷氨酸释放在同步发展中的作用也将在体内进行研究。本项目优势在于结合多电极电生理学、星形胶质细胞中mGluR1通路的分子解剖和计算分析。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Brain cells are of two types. Neurons are the most well-known; they communicate with each other by generating spikes of electrical activity. The second cell type, glial cells, play a variety of roles that are less well understood. In the awake adult brain, the overall spiking activity of neurons appears random. However, in deep sleep or under anesthesia, the spiking activity pattern becomes synchronized within and between various brain regions. During brain development, this type of synchronous spiking is thought to be necessary for the circuit maturation, and the establishment and maintenance of the functional organization of the brain. The focus of this research is to understand the role of one type of glial cell (astrocytes) in the emergence of synchronous spiking activity patterns in the developing brain. The main hypothesis is that astrocytes play a decisive role in the synchronization of neuronal activity in the brain. Preliminary data has demonstrated that astrocytes are necessary for synchronization of spiking activity; the proposed research will elucidate the molecular pathways within astrocytes that control the synchronization of spiking in surrounding neurons. The results of this research will identify fundamental mechanisms of astrocyte-neuron interactions that shape synchronous activity during brain development. This project is conducted at a Historically Black University, and will immerse minority students in cutting edge neuroscience research, and foster peer-mentoring based on interactions between undergraduate and graduate researchers.Preliminary data using mixed neuron and astrocyte cultures on multi-electrode arrays (MEAs) showed random spiking activity which synchronized over time, in comparison to astrocyte-free neuronal cultures, which only show random activity without synchronization. The main hypothesis of this research is that astrocytic release of glutamate mediated by the mGluR1 G-protein-coupled-receptor (GPCR) pathway mediates the effects of astrocytes on the development of neuronal synchronous activity. A model for the mechanism by which the astrocyte mGluR1 pathway mediates neuronal synchronization will be tested using several different dominant negative constructs. A dominant-negative mGluR1 receptor that blocks downstream signaling will be used to understand this signaling pathway's role in both population synchrony, and in the temporal relationship between calcium oscillations within astrocytes and the development of neuronal synchronous bursts. A dominant-negative SNARE protein Vamp2/Syb2 will be used to block glutamate release from astrocytes. The role of the mGluR1 pathway and mGluR1 mediated glutamate release in the development of synchrony will also be examined in vivo. The strength of this project is the combination of multi-electrode electrophysiology, molecular dissection of the mGluR1 pathway in astrocytes, and computational analyses.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.