DIFFUSION OF SUBSTANCES THROUGH THE BRAIN

描述（研究者摘要）：总体目标是 表征物质如何在细胞外空间扩散， 个脑袋 这将阐明细胞外空间的结构， 证明了细胞外化学通讯的潜力。 的 这项研究将有助于改善治疗干预， 药物和生物活性物质。 适当的解决办法 扩散方程将被用来解释实验 结果 所有的实验都将在各种大脑切片上进行 Sprague-Dawley大鼠。 三个具体目标是：1） 2）量化扩散 和多巴胺的摄取3）描述了在发育中的大脑中的扩散。 具体目标1是进一步发展定量光学成像， 扩散分析的相关理论。 新的实验和理论 这些方法将使用高分辨率的分子成像技术， 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 细胞外容积分数以及表观迂曲度 细胞外空间的同质和异质区域， 扩散物质损失到细胞内区室， 在切片的表面。 这些方法具有广泛的适用性 除了这个提议。 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及其数值解 扩散方程将描述多巴胺释放的行为， 压力从微管喷射到新纹状体， 大脑和黑质。 这项工作将有助于决定 多巴胺作为突触外容量传递剂的潜力 并将为多巴胺替代的建模提供数据 改善帕金森病的策略。 具体目标3是表征该化合物的扩散性质。 细胞外空间在正常发育的脑中和在缺氧下， 缺血和渗透压。 荧光葡聚糖和蛋白质将被 与定量光学成像一起使用，以确定 细胞外间隙的结构影响了细胞外间隙切片中的扩散。 新皮层，从纳塔尔后第1天到第21天以及在成年大脑中。 切片还将经受有和没有葡萄糖的缺氧（以 模拟缺血）和低渗和高渗应激，以观察 发育中的大脑结构会对这些伤害做出反应 蒙特卡罗 模拟将被编程为对无法描述的数据进行建模 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 发展过程和如何敏感的是结构 细胞外空间在不同年龄的各种侮辱。

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.