Perinatal white matter development and fetal hypoxia

描述（由申请人提供）：脑瘫（CP）是新生儿重症监护幸存者神经功能障碍的主要原因。进展的障碍是缺乏合适的CP动物模型和缺乏胎儿脑损伤的诊断工具；这两个问题在本建议中都有涉及。我们将利用我们最近开发的一种临床相关的模仿急性胎盘功能不全的胎动物模型，该模型在妊娠70%时胎儿缺氧缺血（H-l）后的新生兔幼崽中显示出CP表型。我们之前的研究表明，在该模型中，H-l后胎儿大脑中产生活性氧（ROS）和活性氮（RNS），母亲服用抗氧化剂可改善胎儿脑损伤并逆转高渗。初步研究表明，白质损伤伴少突胶质细胞（OL）前体死亡是由H-l损伤引起的。我们的方法侧重于早产儿脑白质损伤及其后遗症的细胞和分子决定因素，并采用多学科创新方法，整合了免疫组织化学、流式细胞术、磁共振成像（MRI）电生理学、髓鞘形成和氧化生物化学的最新进展。我们的假设是，早产白质对H-l损伤的偏好与OL前体的成熟依赖性脆弱性有关，OL前体的死亡是随后髓鞘发育障碍发生的致病因素。我们还将验证OL前体对H-l的脆弱性与胎儿大脑中活性氧和活性氮的产生有关的假设。具体目的是确定：(1)胎儿H-l诱导的神经行为改变，特别是P1期高张力，是否与白质损伤有关。(2) H-l中OL前体的死亡是否与随后白质纤维束的损伤有关。(3)活性氧和活性氮在早孕OL前体和白质损伤中的作用。我们的目的是了解导致OL前体死于H-l的因素，并确定体内OL死亡与脑髓鞘发育障碍的发生之间是否存在因果关系。本项目完成后，我们希望通过了解OL影响H-l易感性的内在特征，找到预防白质损伤的策略。更好的临床和生物化学白质损伤标志物的疗效，包括非侵入性MRI测量和安全，无毒的治疗针对胎儿，但给予母亲将进行测试。

DESCRIPTION (provided by applicant): Cerebral palsy (CP) is the leading cause of neurological disability in survivors of neonatal intensive care. The impediments to progress have been a lack of a suitable animal model of CP and a lack of diagnostic tools of fetal brain injury; both are addressed in this proposal. We will utilize a clinically relevant fetal animal mode mimicking acute placental insufficiency recently developed by us, which exhibits a CP phenotype in newborn rabbit pups following fetal hypoxia-ischemia (H-l) at 70% gestation. We have previously shown that reactive oxygen (ROS) and reactive nitrogen species (RNS) are produced in fetal brain after H-l in this model, and administration of antioxidants to the mother ameliorates fetal brain injury and reverses hypertonia. Pilot studies show that white matter (WM) injury accompanied by death of oligodendrocyte (OL) precursors is produced by the H-l insult. Our approach focuses on cellular and molecular determinants of preterm cerebral white matter injury and its sequelae and uses a multidisciplinary innovative approach, integrating recent advances in immunohistochemistry, flow cytometry, magnetic resonance imaging (MRI) electrophysiology, myelination and oxidant biochemistry. Our hypothesis is that the predilection of the preterm white matter to injury from H-l is related to a maturation-dependent vulnerability of OL precursors whose death is a pathogenic factor in the genesis of subsequent myelination disturbances. We will also test the hypothesis that the vulnerability of OL precursors to H-l is related to production of reactive oxygen and nitrogen species in fetal brain. The specific aims are to determine: (1) whether neurobehavioral changes, specifically hypertonia at P1, induced by fetal H-l, are associated with white matter injury. (2) whether death of OL precursors from H-l is associated with subsequent injury to fiber tracts in the white matter. (3) the role of reactive oxygen and nitrogen species in OL precursor and white matter injury at premature gestation. Our objectives are to understand the factors that predispose OL precursors to death from H-l and to establish whether there is a causal relationship between OL death in vivo and the genesis of cerebral myelination disturbances. Upon completion of this project, we hope to gain insight into strategies to prevent white matter injury by understanding intrinsic features of the OL which influence susceptibility to H-l. Efficacy of better clinical and biochemical markers of white matter injury including non-invasive MRI measures and safe, non-toxic therapies aimed at the fetus but administered to the mother will be tested.