ASCORBATE AND GLUTATHIONE IN CNS INJURY

抗坏血酸和谷胱甘肽在中枢神经系统损伤中的作用

基本信息

批准号：
6112550
负责人：
Margaret E Rice
金额：
--
依托单位：
NEW YORK UNIVERSITY SCHOOL OF MEDICINE
依托单位国家：
美国
项目类别：
财政年份：
1998
资助国家：
美国
起止时间：
1998-06-01 至 1999-05-31
项目状态：
已结题

项目摘要

Cerebral antioxidants are neuroprotective agents that prevent oxidative injury during normal aerobic metabolism. Ascorbic acid (ascorbate) and glutathione (GSH) are the most abundant antioxidants of low molecular weight in the CNS. At the onset of ischemic injury, energy-dependent mechanisms that maintain cellular levels of ascorbate and GSH fail, so that they and other small molecules are lost brain cells. The underlying premise of this proposal is that loss of intracellular ascorbate and GSH during ischemia leaves brain cells vulnerable to oxidative damage. Despite the central role of ascorbate and GSH in the antioxidant network, surprising little is known about the mechanisms that regulate their homeostasis in the CNS. The long-term objective of the studies is to determine the mechanisms that regulate antioxidant homeostasis in the CNS, which is a necessary first step in the development of appropriate therapies. Preliminary data indicate ascorbate and GSH levels decrease with age and vary with gender. These data are consistent with human epidemiology, which indicate that stroke incidence and severity increase with age and are greater in males than in females. Proposed studies, therefore, will necessarily address factors that govern age and sex differences. Experiments will use HPLC to determine total tissue ascorbate and GSH, and histological methods to evaluate tissue damage and antioxidant neuroprotection. In addition, tools are available to monitor the extracellular levels of ascorbate ([Asc]o). Using voltammetry with carbon fiber microelectrodes, we will detect [Asc]o in brain slice in vitro and after middle cerebral artery occlusion (MCAO) in vivo, then combine these data with total tissue ascorbate content to calculate [Asc]i. Specific aims are: 1. To determine the differential localization of ascorbate and GSH in the CNS, with emphasis on the hypothesis that ascorbate is in neurons and GSH is in glia. We will confirm antioxidant loss in the aging brain and extend gender studies to include antioxidant enzymes and iron. II. To evaluate the mechanism of intra-and extracellular ascorbate homeostasis. In vitro experiments will test the hypothesis that intra- and extracellular ascorbate concentrations ([Asc]i and [Asc]o) are regulated homeostatically and that the dynamics of this process change with age. III. To evaluate where and how ascorbate and GSH protect. In vitro experiments will test the hypotheses that ascorbate and GSH act intracellularly. IV. To determine mechanisms of ascorbate and GSH loss in ischemia. We will extend preliminary data indicating that loss of antioxidants during ischemia is greater in male rats than in females. V. To determine the relationship between loss of intracellular ascorbate and in focal ischemia. Experiments will test the hypothesis that regions with the greatest loss of [Asc]i during ischemia have the greatest extent of damage.

脑抗氧化剂是神经保护剂，可预防氧化正常有氧代谢期间的损伤。抗坏血酸（抗坏血酸）和谷胱甘肽（GSH）是低分子的最丰富的抗氧化剂中枢神经系统的重量。在缺血性损伤开始时，能量依赖性维持抗坏血酸和GSH失败的细胞水平的机制，以便它们和其他小分子丢失了脑细胞。基础该提议的前提是细胞内抗坏血酸和GSH的丧失在缺血期间，脑细胞容易受到氧化损伤的影响。尽管抗坏血酸和GSH在抗氧化网络中的核心作用，关于调节其的机制知之甚少中枢神经系统的体内平衡。研究的长期目标是确定CNS中调节抗氧化剂稳态的机制，这是开发适当的第一步疗法。初步数据表明抗坏血酸和GSH水平降低随着年龄的增长，随着性别的变化。这些数据与人类一致流行病学表明中风发生率和严重程度增加随着年龄的增长，男性比女性更大。拟议的研究，因此，必然应对支配年龄和性别的因素差异。实验将使用HPLC来确定总组织抗坏血酸和GSH，以及评估组织损伤和抗氧化剂的组织学方法神经保护。此外，可以使用工具来监视抗坏血酸的细胞外水平（[ASC] O）。将伏安法与碳一起使用纤维微电极，我们将在体外检测到脑切片中的[ASC] O 在体内脑动脉闭塞（MCAO）之后，然后将这些结合起来具有整体组织抗坏血酸含量的数据来计算[ASC] i。具体的目的是： 1。确定抗坏血酸和GSH在中枢神经系统强调了抗坏血酸是神经元和GSH的假设是在神经胶质的。我们将确认大脑衰老的抗氧化剂损失并延伸性别研究包括抗氧化剂酶和铁。 ii。评估细胞内抗坏血酸稳态的机制。体外实验将检验细胞内和细胞外的假设抗坏血酸浓度（[ASC] I和[ASC] O）受到调节的调节并且这个过程的动态随着年龄的增长而变化。 iii。评估抗坏血酸和GSH的何处以及如何保护。体外实验将测试抗坏血酸和GSH在细胞内起作用的假设。 iv。到确定缺血中抗坏血酸和GSH损失的机制。我们将扩展初步数据表明缺血期间抗氧化剂的丧失是雄性大鼠比女性大。 V.确定关系在细胞内抗坏血酸和局灶性缺血之间的丧失之间。实验将检验以下假设，即[ASC] I损失最大的区域在缺血期间，损害的程度最大。