Tetrahydrobiopterin in Hypoxia-Ischemia Induced Fetal Brain Dysfunction

四氢生物蝶呤在缺氧缺血引起的胎儿脑功能障碍中的作用

• 批准号: 7234659
• 负责人: JEANNETTE M. VASQUEZ VIVAR
• 金额: $ 21.03万
• 依托单位: MEDICAL COLLEGE OF WISCONSIN
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-04-01 至 2009-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7234659
• 关键词: Acute; Affect; Antioxidants; Arginine; Arts; Biochemical; Biopterin; Brain; Brain Hypoxia-Ischemia; Brain Injuries; Brain Part; Calcium; Cells; Cerebral Palsy; Child; Chronic; Citrulline; Clinical; Cognitive; Defect; Detection; Development; Developmental Biology; Disease; Dopa-Responsive Dystonia; Dystonia; Enzymes; Equilibrium; Etiology; Event; Free Radicals; Functional disorder; Generations; Genetic Models; Glutamates; Goals; High Pressure Liquid Chromatography; Homeostasis; Human; Hydrogen Peroxide; Hypoxia; Impaired cognition; Injury; Levodopa; Light; Link; Measurement; Measures; Mediating; Medical; Metabolism; Methods; Modeling; Motor Seizures; Mus; Muscle Hypertonia; N-Methyl-D-Aspartate Receptors; Neonatal; Neopterin; Nervous System Physiology; Neurologic; Nitric Oxide; Nitric Oxide Synthase Type I; Oral; Oryctolagus cuniculus; Oxidants; Oxidation-Reduction; Oxidative Stress; Oxygen; Pathway interactions; Perinatal Brain Injury; Perinatal Hypoxia; Play; Predisposition; Prevention; Preventive; Production; Protocols documentation; Reactive Nitrogen Species; Receptor Activation; Reporting; Research Personnel; Risk Factors; Role; Staining method; Stains; Superoxides; Supplementation; Techniques; Testing; Therapeutic; Therapeutic Intervention; Variant; Western Blotting; age related; ascorbate; base; cold temperature; dihydroethidium; dimer; disability; dopaminergic neuron; excitotoxicity; fetal; indexing; inhibitor/antagonist; monomer; motor deficit; motor impairment; neonate; omega-N-Methylarginine; outcome forecast; prevent; response; tetrahydrobiopterin

DESCRIPTION (provided by applicant): The broad objective of this proposal is to determine the link between hypoxia-ischemia (H-I) and loss of tetrahydrobiopterin (BH4) and neurological function in the preterm fetal brain. The mechanism by which H-I causes damage to the developing brain remains unknown, although evidence indicates that oxidative stress plays a role. Loss of dopaminergic neurons may occur as a consequence. Congenital BH4 deficiency causes motor deficits that, in some cases, can be treated with BH4. We recently presented a model of global H-I injury in preterm fetal rabbit brain that causes hypertonia and motor deficits in the neonates and shows that BH4 levels in the preterm fetal rabbit brain are much lower compared to those reported in the hph-1 mice, a model for genetic BH4 deficiency and L-dopa-responsive-dystonia. Thus, low BH4 levels may be a critical developmental factor associated with H-I induced fetal brain dysfunction. We also showed that limited BH4 levels supports nNOS uncoupling to increase superoxide formation. Thus, preterm fetal rabbit brain gives investigators an opportunity that was not available before to ascertain the connection between H-I and BH4- dependent mechanisms (NO, superoxide, L-dopa) in the etiology of motor impairments. Hypothesis: High oxidative stress induced by hypoxia-ischemia disrupts BH4-homeostasis in the preterm fetal brain leading to motor deficits. Aims: 1) Examine whether the developmental susceptibility of the premature brain can be explained by BH4 modulation of superoxide and NO production from nNOS; 2) Examine the acute and chronic mechanisms causing loss of BH4 and nNOS uncoupling after H-I; and the effects of BH4 supplementation alone or in combination with ascorbate, a BH4 stabilizing antioxidant. Methods: Brain BH4, 7,8-BH2 and neopterin levels and activity of BH4-dependent enzymes will be measured by HPLC. Superoxide quantification following conversion of dihydroethidium to 2-hydroxyethidium will be performed by HPLC. nNOS activity will be followed by 14 C-citrulline and NO-derived chemiluminescence. Significance: Perinatal H-I is an important risk factor for disability in children often resulting in cognitive and motor impairment (cerebral palsy). Currently, there is no effective treatment to prevent the consequences of H-I mediated injury to the developing brain. The information obtained from this proposal will provide the basis to define the use of BH4 in preventing fetal brain dysfunction. Hypoxia-ischemia (H-I) or low oxygen supply is considered a major risk factor for brain damage in the immature fetal brain. Currently, there are no interventional measures to prevent or decrease brain damage after any clinical situation where deficient oxygen supply is suspected. The complications and prognosis of H-I are age related, indicating the importance of developmental factors in the disease. Tetrahydrobiopterin is a key metabolite in the brain regulating several functions and oxidant production. It is possibly involved in brain dysfunction, following H-I. We expect to provide important new information on the developmental biology of tetrahydrobiopterin and its involvement in the mechanisms of oxidative damage in fetal brain. This information will likely define the use of tetrahydrobiopterin in the prevention and/or amelioration of H-I induced fetal brain dysfunction, which remains a major medical challenge.

描述（由申请人提供）：本提案的主要目的是确定缺氧缺血（H-I）和四氢生物蝶呤（BH 4）缺失与早产胎儿脑神经功能之间的联系。H-I对发育中的大脑造成损害的机制仍然未知，尽管有证据表明氧化应激起作用。多巴胺能神经元的损失可能会因此而发生。先天性BH 4缺乏导致运动缺陷，在某些情况下，可以用BH 4治疗。我们最近提出了一个模型的全球H-I损伤早产儿胎兔脑，导致张力亢进和运动缺陷的新生儿，并表明，BH 4水平在早产儿胎兔脑中是低得多的hph-1小鼠，遗传BH 4缺乏症和L-多巴反应性肌张力障碍的模型相比，报告。因此，低BH 4水平可能是与H-I诱导的胎儿脑功能障碍相关的关键发育因素。我们还表明，有限的BH 4水平支持nNOS解偶联，以增加超氧化物的形成。因此，早产胎兔脑给研究人员提供了一个机会，这是以前没有的，以确定H-1和BH 4依赖性机制（NO，超氧化物，左旋多巴）之间的联系，在运动障碍的病因。假设：缺氧-缺血诱导的高氧化应激破坏了早产胎儿脑中BH 4的稳态，导致运动缺陷。目的：1）检查早产儿大脑的发育易感性是否可以通过BH 4对nNOS产生的超氧化物和NO的调节来解释; 2）检查H-I后引起BH 4和nNOS解偶联损失的急性和慢性机制;以及单独补充BH 4或BH 4与抗坏血酸盐（一种BH 4稳定性抗氧化剂）组合的作用。方法：采用高效液相色谱法测定脑内BH 4、7，8-BH 2和新蝶呤水平及BH 4依赖酶活性。将通过HPLC法对二氢乙锭转化为2-羟基乙锭后的超氧化物进行定量。nNOS活性之后将进行14 C-瓜氨酸和NO衍生的化学发光。意义：围产期H-I是儿童残疾的重要危险因素，通常导致认知和运动障碍（脑瘫）。目前，没有有效的治疗方法来预防H-I介导的对发育中的大脑的损伤的后果。从该提案中获得的信息将为确定BH 4在预防胎儿脑功能障碍中的用途提供基础。缺氧缺血（H-I）或低氧供应被认为是未成熟胎儿脑损伤的主要危险因素。目前，没有干预措施，以防止或减少脑损伤后，任何临床情况下，缺氧供应怀疑。H-I的并发症和预后与年龄有关，表明发育因素在疾病中的重要性。四氢生物蝶呤是大脑中调节多种功能和氧化剂产生的关键代谢物。它可能与H-I后的脑功能障碍有关。我们期望提供重要的新信息的发育生物学的四氢生物蝶呤和其参与的机制，在胎儿脑氧化损伤。该信息将可能定义四氢生物蝶呤在预防和/或改善H-I诱导的胎儿脑功能障碍中的用途，这仍然是一个主要的医学挑战。