BIOCHEMICAL CONTROL OF BBB IN ABNORMAL BRAIN CAPILLARIES

EXCEED提供的空间。脑毛细血管内皮细胞及其毗邻的细胞、周细胞和星形胶质细胞是血脑屏障的结构和功能成分。在受损的脑和脑肿瘤中，伴随着毛细血管功能属性改变的生化变化被认为分别损害了血脑屏障和血-肿瘤屏障(BTB)的通透性。BTB和损伤的BBB可以用血管调节剂如缓激肽和白三烯重复地瞬时打开，以选择性地将药物输送到脑肿瘤和脑损伤部位。特别是，我们的结果表明，缓激肽介导的BTB的开放依次涉及缓激素2型(B2)受体、一氧化氮(NO)、环GMP(CGMP)和钙依赖性钾(KCA)通道。然而，这些分子内源性产生或发生的细胞位置，以及它们如何影响完好和受损大脑以及脑肿瘤中毛细血管的通透性特征，目前尚不清楚。这项建议试图获得对单个细胞类型的作用的洞察，这些细胞类型解释了体内脑毛细血管的不同渗透性反应。一个主要的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，并将这些指标与体内血脑屏障和血脑屏障的通透性联系起来。短期脑缺血再灌注所致脑瘤和脑损伤的大鼠模型将被用于拟议的研究。我们将确定缓激肽的细胞结合部位，并确定BTB对缓激肽的耐受性反应和对不同大小分子的通透性常数(Ki)是否由于功能B2受体的行为或密度分布的改变而引起。生化、共聚焦显微镜、分子、药理学和电子显微镜的研究主要集中在B2受体、NO、可溶性鸟苷环化酶、cGMP依赖的蛋白激酶和KCA通道。透射电子显微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管腔-血管腔梯度的内皮泡状通路(S)或通过对血管调节剂的其他反应(S)选择性地穿过正常或受损的血脑屏障和血脑屏障。通透性研究将确定KCA通道是否构成调节BBB和BTB通透性的几个生化调节剂的汇聚点。这些研究将有助于描述构成血脑屏障的操作机制，以及导致不同大小的分子选择性地输送到异常或受损的脑微血管的机制。建议的研究结果可能对选择性和加强神经药物、抗肿瘤药物和大型病毒载体到异常大脑区域的治疗神经疾病具有重要意义。表演网站========================================Section End===========================================

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===========================================