RADIATION-INDUCED INJURY IN CEREBRAL ENDOTHELIAL CELLS--ROLE OF OXIDATIVE STRESS

手术后的放射治疗是最有效的治疗方法， 恶性脑肿瘤，但临床上可接受的辐射剂量是 因为辐射也会损害正常组织。 如果损伤 可以改善，放射剂量提供给脑肿瘤可能是 提高了治疗效果。 放射性脑 损伤通常包括对脑血管系统的损伤， 明显的血脑屏障破坏和脑水肿。 在这 研究，我们希望阐明负责敏感性的机制 对构成脑血管系统的细胞的辐射。 这 这项工作可能会提出一些可能的治疗方法， 正常大脑的辐射敏感性。 我们假设， 内源性抗氧化剂，如抗坏血酸，和促氧化剂， 例如天然存在的自由基一氧化氮（NO）， 负责脑血管的任何不同的放射敏感性 细胞：内源性氧化剂水平的改变可以调节 辐射敏感性 为了验证这一假设，我们将检查 脑内皮细胞，星形胶质细胞， 以及来自正常大鼠和小鼠以及过表达 人铜锌超氧化物歧化酶（CuZn）， 各种抗氧化剂和促氧化剂。 我们的具体目标是：1） 定量大鼠大脑皮层原代细胞培养物的易感性 内皮细胞、星形胶质细胞和周细胞对辐射诱导的损伤; 2)将脑血管细胞辐射损伤与 抗氧化剂的水平; 3）确定是否有生理刺激 NO的产生增强放射性脑血管内皮损伤 细胞，以确定NO的阻断是否可以减轻这种损伤， 确定超氧阴离子在NO介导的损伤中的作用; 4)为了阐明修饰的分子机制， 内源性抗氧化系统（SOD、过氧化氢酶和谷胱甘肽过氧化物酶） 或NO的产生调节辐射诱导的细胞损伤的程度; 以及，5）确定辐射诱导的损伤水平是否 当细胞作为混合培养物（内皮-周细胞和 内皮-星形胶质细胞），以及是否有任何反应的改变， 由于抗氧化剂的细胞间转移， 抗氧化剂的生产，或转移自由基，如NO。

Radiation therapy following surgery is the most effective treatment for malignant brain tumors, but clinically admissible radiation doses are limited because the radiation also damages normal tissue. If that damage could be ameliorated, radiation doses delivered to brain tumors might be increased and therapeutic efficacy enhanced. Radiation-induced brain damage often includes damage to the cerebral vasculature, as evidenced by prominent blood-brain barrier breakdown and cerebral edema. In this study, we wish to elucidate the mechanisms responsible for the sensitivity to radiation of the cells composing the cerebral vascular system. This work could suggest possible therapies directed toward ameliorating the radiation sensitivity of normal brain. We hypothesize that the differing endogenous levels of antioxidants, such as ascorbate, and pro-oxidants, such as the naturally occurring free radical nitric oxide (NO), are responsible for any differential radiosensitivity of cerebrovascular cells: and that modification of endogenous oxidant levels can modulate radiosensitivity. To test this hypothesis, we will examine the radiation sensitivity of primary cultures of cerebral endothelial cells, astrocytes, and pericytes from normal rats and mice and transgenic mice overexpressing human copper-zinc (CuZn)-superoxide dismutase (SOD) in the presence of various antioxidants and pro-oxidants. Our specific aims are: 1) to quantify the susceptibility of primary cell cultures of rat cerebral endothelial cells, astrocytes, and pericytes to radiation-induced injury; 2) to correlate radiation-induced injury to cerebrovascular cells with levels of antioxidants; 3) to determine whether physiologic stimulation of NO production enhances radiation-induced injury to cerebral endothelial cells, to determine whether blockage of NO can ameliorate such injury, and to establish any role the superoxide anion may have in NO-mediated damage; 4) to elucidate the molecular mechanism by which modification of endogenous antioxidant systems (SOD, catalase, and glutathione peroxidase) or production of NO modulate the degree of radiation-induced cell damage; and, 5) to determine whether the level of radiation-induced injury is altered when cells are grown as mixed cultures (endothelial-pericyte and endothelial-astrocyte), and whether any modification of the response is due to cell-to-cell transfer of antioxidants, to the induction of antioxidant production, or to transfer of free radicals such as NO.