Department of Physiology, Soroka University Medical Center and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
Neuroimage. 2010 Jan 1;49(1):337-44. doi: 10.1016/j.neuroimage.2009.08.009. Epub 2009 Aug 12.
The brain is characterized by an extremely rich blood supply, regulated by changes in blood vessel diameter and blood flow, depending on metabolic demands. The blood-brain barrier (BBB)-a functional and structural barrier separating the intravascular and neuropil compartments-characterizes the brain's vascular bed and is essential for normal brain functions. Disruptions to the regional cerebral blood supply, to blood drainage and to BBB properties have been described in most common neurological disorders, but there is a lack of quantitative methods for assessing blood flow dynamics and BBB permeability in small blood vessels under both physiological and pathological conditions. Here, we present a quantitative image analysis approach that allows the characterization of relative changes in the regional cerebral blood flow (rCBF) and BBB properties in small surface cortical vessels. In experiments conducted using the open window technique in rats, a fluorescent tracer was injected into the tail vein, and images of the small vessels at the surface of the cortex were taken using a fast CCD camera. Pixel-based image analysis included registration and characterization of the changes in fluorescent intensity, followed by cluster analysis. This analysis enabled the characterization of rCBF in small arterioles and venules and changes in BBB permeability. The method was implemented successfully under experimental conditions, including increased rCBF induced by neural stimulation, bile salt-induced BBB breakdown, and photothrombosis-mediated local ischemia. The new approach may be used to study changes in rCBF, neurovascular coupling and BBB permeability under normal and pathological brain conditions.
大脑的血液供应非常丰富，其血管直径和血流量会根据代谢需求发生变化，从而得到调节。血脑屏障（blood-brain barrier，BBB）是一种分隔血管腔和神经胶质细胞间隙的功能性和结构性屏障，它是大脑血管床的特征，对正常的大脑功能至关重要。在大多数常见的神经疾病中，都描述了区域性脑血流、血液引流和 BBB 特性的破坏，但缺乏用于评估生理和病理条件下小血管中血流动力学和 BBB 通透性的定量方法。在这里，我们提出了一种定量图像分析方法，该方法可用于表征小皮质表面血管中区域性脑血流（rCBF）和 BBB 特性的相对变化。在使用大鼠开颅窗口技术进行的实验中，荧光示踪剂被注入尾静脉，并用快速 CCD 相机拍摄皮质表面小血管的图像。基于像素的图像分析包括荧光强度变化的注册和特征描述，随后是聚类分析。这种分析能够表征小动脉和小静脉中的 rCBF 以及 BBB 通透性的变化。该方法在实验条件下成功实施，包括神经刺激引起的 rCBF 增加、胆汁盐诱导的 BBB 破坏和光血栓形成介导的局部缺血。该新方法可用于研究正常和病理脑条件下 rCBF、神经血管耦合和 BBB 通透性的变化。
