DIFFUSION OF SUBSTANCES THROUGH THE BRAIN

描述（研究者摘要）：总体目标是 描述物质如何在细胞外空间扩散 大脑。 这将阐明细胞外空间的结构， 证明细胞外化学通讯的潜力。 的 研究将有助于改善治疗干预和援助目标 脑组织中的药物和生物活性物质。 适当的解决方案 扩散方程将用于解释实验 结果。 所有实验都将在不同大脑的切片上进行 Sprague-Dawley 大鼠的区域。 这三个具体目标是：1) 改进测量扩散的光学方法 2) 量化扩散 和多巴胺的摄取 3) 描述了发育中大脑的扩散。 具体目标 1 是进一步发展定量光学成像和 分析扩散的相关理论。 新的实验和理论 方法将使用标记分子的高分辨率成像 荧光染料。 该技术将扩展到荧光葡聚糖 分子量和蛋白质超过 70 kDa。 它将测量 细胞外体积分数以及表观弯曲度 细胞外空间和帐户的同质和异质区域 用于扩散物质损失到细胞内室和 在切片的表面。 这些方法将具有广泛的适用性 超出本提案。 具体目标 2 是研究 Michaelis-Menten 的相对作用 多巴胺在细胞外迁移的动力学和扩散 空间。 快速扫描循环伏安法和数值解 扩散方程将描述多巴胺释放的行为 压力从微量移液器射入新纹状体，即细胞核 伏隔核和黑质。 这项工作将有助于决定 多巴胺作为突触外容量传输剂的潜力 并将为多巴胺替代建模提供数据 改善帕金森病的策略。 具体目标 3 是表征扩散特性 正常发育的大脑和缺氧条件下的细胞外空间， 缺血和渗透应激。 荧光葡聚糖和蛋白质将 与定量光学成像一起使用以确定如何变化 细胞外空间的结构影响细胞切片中的扩散 新皮质，从出生后第 1 天到第 21 天以及成人大脑中。 切片也会受到有或没有葡萄糖的缺氧（以 模拟缺血）以及低渗和高渗应激，看看如何 发育中的大脑结构会对这些侮辱做出反应。 蒙特卡洛 模拟将被编程为无法描述的模型数据 扩散方程的解析解或数值解。 这些 实验将有助于讨论扩散在 发育过程以及结构的易受影响程度 不同年龄的细胞外空间会受到不同的损伤。

DESCRIPTION (Investigator's Abstract): The overall goal is to characterize how substances diffuse in the extracellular space of the brain. This will clarify the structure of extracellular space, demonstrate the potential for extracellular chemical communication. The study will help improve therapeutic intervention and aid targeting of drugs and bioactive substances in brain tissue. Appropriate solutions to the diffusion equation will be used to interpret experimental results. All experiments will be made on slices from various brain regions of Sprague-Dawley rats. The three Specific Aims are to: 1) improve optical methods for measuring diffusion 2) quantify the diffusion and uptake of dopamine 3) describe diffusion in the developing brain. Specific Aim 1 is further development of quantitative optical imaging and related theory for analyzing diffusion. New experimental and theoretical methods will use high-resolution imaging of molecules tagged with fluorescent dyes. The technique will be extended to fluorescent dextrans above 70 kDa in molecular weight and proteins. It will measure extracellular volume fraction as well as apparent tortuosity in homogeneous and heterogeneous regions of extracellular space and account for loss of the diffusing substance to the intracellular compartment and at the surfaces of slices. These methods will have wide applicability beyond this proposal. Specific Aim 2 is to study the relative roles of Michaelis-Menten kinetics and diffusion in the migration of dopamine in the extracellular space. Fast-scan cyclic voltametry and numerical solutions to the diffusion equation will describe the behavior of dopamine release by pressure ejection from a micropipette into the neostriatum, the nucleus accumbens and the substantia nigra. This work will help to decide the potential of dopamine as an agent for extra-synaptic volume transmission and will provide data for the modeling of dopamine replacement strategies to ameliorate Parkinson's Disease. Specific Aim 3 is to characterize the diffusion properties of the extracellular space in the normal developing brain and under hypoxia, ischemic and osmotic stress. Fluorescent dextrans and proteins will be used with quantitative optical imaging to determine how the changing structures of the extracellular space affect diffusion in slices of the neocortex, from post- natal day 1 to day 21 and in the adult brain. Slices will also be subjected to hypoxia with and without glucose (to simulate ischemia) and to hypo- and hyperosmotic stress to see how the developing brain structure reacts to these insults. A Monte Carlo simulation will be programmed to model data that cannot be described by analytical or numerical solutions to the diffusion equation. These experiments will aid discussions of the role of diffusion in the developmental process and how susceptible is the structure of extracellular space to various insults at different ages.