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。神经元是最广为人知的；它们通过产生电活动的尖峰来相互交流。第二种细胞类型，神经胶质细胞，扮演着各种不同的角色，但人们对此知之甚少。在清醒的成人大脑中，神经元的整体放电活动似乎是随机的。然而，在深度睡眠或麻醉状态下，尖峰活动模式在不同的大脑区域内和之间变得同步。在大脑发育期间，这种类型的同步尖峰被认为是脑回路成熟以及大脑功能组织的建立和维持所必需的。这项研究的重点是了解一种类型的胶质细胞(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所起的作用。主要的假设是，星形胶质细胞在大脑中神经元活动的同步化中起着决定性的作用。初步数据表明，星形胶质细胞是同步放电活动所必需的；拟议的研究将阐明星形胶质细胞内控制周围神经元同步放电的分子通路。这项研究的结果将确定在大脑发育过程中形成同步活动的星形胶质细胞-神经元相互作用的基本机制。这个项目是在一所历史悠久的黑人大学进行的，将让少数族裔学生沉浸在尖端的神经科学研究中，并基于本科生和研究生之间的互动促进同行指导。使用多电极阵列(MEA)上的混合神经元和星形胶质细胞培养的初步数据显示，随着时间的推移，随机放电活动是同步的，而不含星形胶质细胞的神经元培养只显示出随机活动，而不同步。本研究的主要假设是星形胶质细胞通过mGluR1G蛋白偶联受体(GPCR)途径释放谷氨酸，介导星形胶质细胞对神经元同步活动发育的影响。将使用几种不同的显性负结构来测试星形胶质细胞mGluR1通路介导神经元同步的机制的模型。一个阻断下游信号的显性负性mGluR1受体将被用来理解这一信号通路在种群同步以及星形胶质细胞内钙振荡和神经元同步爆发发展之间的时间关系中的作用。显性负性SNARE蛋白Vamp2/Syb2将被用来阻止星形胶质细胞释放谷氨酸。MGluR1途径和mGluR1介导的谷氨酸释放在同步性发育中的作用也将在体内进行检验。该项目的优势是结合了多电极电生理学、星形胶质细胞中mGluR1途径的分子解剖和计算分析。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.