BIOCHEMICAL CONTROL OF BBB IN ABNORMAL BRAIN CAPILLARIES

超出规定的空间。脑毛细血管内皮及其相邻细胞周细胞和星形胶质细胞是血脑屏障（BBB）的结构和功能成分。在脑损伤和脑肿瘤中，伴随毛细血管功能属性改变的生化变化被认为分别损害血脑屏障和血肿瘤屏障（BTB）的通透性。血管调节剂如缓激肽和白三烯可使BTB和损伤的血脑屏障瞬间打开，从而在体内可选择性地向脑肿瘤和脑损伤部位递送药物。特别是，我们的研究结果表明，缓激肽介导的BTB开放顺序涉及缓激肽2型（B2）受体、一氧化氮（NO）、环GMP （cGMP）和钙依赖性钾（Kca）通道。然而，这些分子产生或内源性发生的细胞部位，以及它们如何影响完好脑、损伤脑和脑肿瘤中毛细血管的通透性特性，都是未知的。该建议旨在深入了解个体细胞类型在体内脑毛细血管中不同通透性反应中的作用。主要目标是确定毛细血管成分和效应分子的结构和功能的精确时空变化，并将这些指标与血脑屏障和BTB的通透性联系起来。大鼠脑肿瘤和短期缺血再灌注脑损伤模型将用于拟议的研究。我们将确定慢激肽的细胞结合位点，并确定BTB对慢激肽的难反应和不同大小分子的渗透性常数（Ki）是否是由于功能性B2受体的行为或密度分布的改变。生物化学、共聚焦显微镜、分子、药理学和电镜研究主要集中在B2受体、NO、可溶性鸟苷酸环化酶、cgmp依赖性蛋白激酶和Kca通道。透射电镜研究将确定不同大小的分子和病毒颗粒是否通过紧密连接或沿光腔梯度的跨内皮泡途径或通过对血管调节剂的其他反应选择性地通过正常或受损血脑屏障和BTB传递。渗透性研究将确定Kca通道是否构成调节血脑屏障和BTB渗透性的几种生化调节剂的会聚点。这些研究将有助于描述血脑屏障的作用机制，以及导致不同大小的分子选择性递送到异常或损伤的脑微血管的机制。拟议研究的结果可能对选择性和增强神经药物，抗肿瘤药物和大型病毒载体到异常脑区域治疗神经系统疾病具有启示意义。网站性能 ======================================== 节结束 ===========================================

EXCEEDTHE SPACE PROVIDED. Brain capillary endothelium, and its contiguous cells, pericytes and astrocytes, are the structural and functional components of the blood-brain barrier (BBB). Biochemical changes concomitant with modified functional attributes of capillaries in injured brain and brain tumors, are believed to compromise BBB and blood-tumor barrier(BTB) permeability, respectively. The BTB and injured BBB can be opened transiently with vasomodulators such as bradykinin and leukotrienes reproducibly for a selective drug delivery to brain tumors and sites of brain injury in vivo. In particular, our results suggest that bradykinin-mediated opening of BTB sequentially involves bradykinin type 2 (B2)receptors, nitric oxide (NO), cyclic GMP (cGMP),, and calcium-dependent potassium (Kca) channels. The cellular sites, however, where such molecules are produced or occur endogenously, and how they affect permeability characteristics of the capillaries in intact and injured brain, and in brain tumors, are unknown. This proposal seeks to obtain insights into the role of individual cell types that account for differential permeability responses in brain capillaries in vivo. A major goal is to determine precise spatio-temporal changes in structure and function of capillary components, and effector molecules, and relate these indices to permeability of the BBB and the BTB in vivo. Rat models of brain tumors and brain injury caused by short-terrn ischemia-reperfusion will be used for proposed studies. We will identify the cellular binding sites for bradykinin, and determine if the refractory response of the BTB to bradykinin and the permeability constant (Ki) for different-sized molecules are due to altered behavior or density distribution of functional B2 receptors. Biochemical, confocal microscopic, molecular, pharmacological and electron microscopic studies are focused on B2 receptors, NO, soluble guanylate cyclase, cGMP-dependent protein kinase and Kca channels. Transmission electron microscopic studies will determine if selective delivery of different sized molecules and viral particles across the normal or injured BBB and BTB occurs via tight junctions or transendothelial vesicular route(s) along a luminal-abluminal gradient or by other response(s) to vasomodulators. Permeability studies will determine if Kca channels constitute a convergence point of several biochemical modulators regulating BBB and BTB permeability. These studies will help delineate the operative mechanisms that constitute the BBB, and the mechanisms that lead to selective delivery of molecules of different size to abnormal or injured brain microvessels. The results of the proposed studies may have implications for selective and enhanced delivery of neuropharmaceutics, anti-neoplastic agents, and large viral vectors to abnormal brain regions for treating neurological diseases. PERFORMANCE SITE ========================================Section End===========================================