CATECHOLAMINES, ANTIOXIDANTS AND OXIDATIVE STRESS

众所周知，由于其固有的氧化还原特性，易自氧化的儿茶酚胺在有氧条件下产生活性自由基和H2O2。因此，儿茶酚胺能神经元固有地受到高氧化应激和自由基损伤。儿茶酚胺能神经元在衰老和中枢神经系统疾病（如帕金森病）以及非法药物（如安非他明）的使用中发生退化，可归因于儿茶酚胺介导的大脑受影响区域过量产生氧自由基和/或H2O2。尽管大多数活性自由基和氧化剂可以被酶防御机制和细胞氧化剂有效清除，但它们的过量产生可能导致广泛的细胞损伤。存在高浓度的抗坏血酸（Asc）、复杂的atp酶驱动、b561介导的Asc再生系统（ARS）、有效的儿茶酚胺摄取机制以及儿茶酚胺储存囊泡中缺乏抗氧化剂（如谷胱甘肽）表明，除了为多巴胺-单氧合酶（DbetaM）和肽基α -羟化单氧合酶（PHM）反应提供电子外，Asc也必须在保护儿茶酚胺能神经元免受儿茶酚胺诱导的自由基损伤中发挥关键作用。因此，质子易位atp酶、ARS或单胺转运体的故障可能导致高氧化应激，从而导致自由基生成的指数级联和广泛的细胞损伤。尽管有这一令人信服的证据，但儿茶酚胺能神经元中整合病理特征的生化机制尚未得到充分探索。因此，更精确地描述(a)儿茶酚胺代谢的生化步骤和(b)抗氧化剂在保护儿茶酚胺免于氧化中的作用，从而缓解氧化应激，可能是我们对儿茶酚胺能神经元功能障碍理解的重大进展。提出的研究的总体目标是使用多学科方法，以染色质颗粒和颗粒鬼为模型，在分子水平上检查单胺转运体、质子易位atp酶、ARS和DbetaM的功能偶联。随着对这些蛋白的功能偶联的更好理解，这些蛋白在保护儿茶酚胺储存囊泡免受氧化应激中的作用以及氧化应激对其个体和协调功能的影响将被研究。

Easily autooxidizable catecholamines are known to generate reactive radicals and H2O2 under aerobic conditions due to their inherent redox properties. Consequently, catecholaminergic neurons are inherently subjected to high oxidative stress and free radical damage. The degneration of catecholaminergic neurons in aging and central nervous system diseases such as Parkinson's Disease, as well as in the use of illicit drugs such as amphetamines have been attributed to the catecholamine mediated excessive production of oxygen free radicals and/or H2O2 in the affected areas of the brain. Although, most of the reactive radical species and oxidants are effectively scavenged by enzymatic defense mechanisms and by cellular oxidants, their excessive generation may lead to extensive cellular damage. Presence of high concentrations of ascorbate (Asc), an intricate ATPase drive, b561-mediated, Asc regenerating system (ARS), and an efficient catecholamine uptake mechanism together with the absence of antioxidants such as glutathione in catecholamine storage vesicles suggest that, in addition to providing electrons for dopamine beta-monooxygenase (DbetaM) and peptidyl alpha- hydroxylating monooxygenase (PHM) reactions, Asc must also play a key role in the protection of catecholaminergic neurons from catecholamine induced free radical damage. Therefore, the malfunctioning of proton translocating ATPase, ARS, or monoamine transporter could result in high oxidative stress leading to an exponentially propagating cascade of radical generation and extensive cellular damage. Despite this convincing evidence, the biochemical mechanisms that my integrate the pathological features in catecholaminergic neurons have not been fully explored. Thus, a more precise description of (a) the biochemical steps in catecholamine metabolism and (b) the role of antioxidants in protecting catecholamines from oxidation, consequently relieving oxidative stress could be a significant advancement in our understanding of the dysfunction of catecholaminergic neurons. The overall objective of the proposed studies is to examine the functional coupling of the monoamine transporter, proton translocating ATPase, ARS, and DbetaM at the molecular level using multidisciplinary approaches using chromaffin granules and granule ghosts as a model. With a better understanding of the functional coupling of these proteins, the role of these proteins in protecting catecholamine storage vesicles from oxidative stress as well as the effect of oxidative stress on their individual and coordinated functions will be examined.