wilso-affy-rat-132990. Rattus norvegicus

Hypoxic-ischemic (HI) injury in the developing brain is a common cause of disability in children, and there are no effective treatments at this time. Exposure to sublethal hypoxic conditions (hypoxic preconditioning) 24 hours prior to hypoxic-ischemic insult is protective in the developing rat model. We have observed protective effects on brain histopathology and on long-term sensory-motor behavioral tasks. Changes in gene expression are thought to underlie this protective effect. By comparing gene expression in rats subjected to hypoxic preconditioning or sham conditioning at several time points from 0 to 24 hrs after preconditioning, we should gain insight into the mechanisms underlying these neuroprotective effects and may identify targets for therapeutic intervention. The aim of this study is to determine the effect of hypoxic preconditioning on global gene expression, and, in littermates, to examine the effect of hypoxic preconditioning 24 h prior to hypoxic-ischemic insult on brain histopathology. We hypothesize that changes in gene expression underlie the protective effect of hypoxic preconditioning against subsequent hypoxic-ischemic insult. Gene expression will be examined in two groups, 1) preconditioned and 2) sham controls, at 4 time points. On postnatal day 6, preconditioned animals are exposed to normothermic hypoxia for 3 hrs (8.0% oxygen, 36 degrees C), and sham animals are simultaneouosly exposed to normoxia at 36 degrees C. Animals are then returned to their dams until euthanized at 4 time points (0h, 2h, 8h, and 24h later). Five brains/group/timepoint will be used, with an equal number of males and females in each group. Brains are removed and dissected on ice. Cerebral cortex is dissected from both hemispheres and rapidly frozen on dry ice. Total RNA is isolated using the QIAGEN RNeasy Protect Maxi Kit. Littermates of these animals will be exposed to hypoxic preconditioning or sham preconditioning and subjected to hypoxic-ischemic injury 24 h later. These animals are euthanized at postnatal day 14 for histopathologic evaluation of injury. Keywords: time-course

发育性脑缺氧缺血（Hypoxic-ischemic, HI）损伤是儿童残疾的常见病因，目前尚无有效治疗手段。在缺氧缺血性损伤前24小时给予亚致死性缺氧处理，即缺氧预适应（hypoxic preconditioning），对发育中的大鼠模型具有保护作用。我们已观察到其对脑组织病理学以及长期感觉运动行为任务的保护效应。现有研究认为，基因表达改变是该保护效应的分子基础。通过对比缺氧预适应组与假处理组（sham conditioning）大鼠在预适应后0至24小时多个时间点的基因表达情况，我们有望阐明这些神经保护效应的潜在机制，并筛选出治疗干预的潜在靶点。本研究旨在明确缺氧预适应对全基因组基因表达的影响，并通过同窝幼鼠，探讨缺氧缺血性损伤前24小时给予缺氧预处理对脑组织病理学的作用。我们提出假说：基因表达改变是缺氧预适应抵御后续缺氧缺血性损伤的保护效应的核心机制。本研究将分为两组进行基因表达检测：1）缺氧预适应组，2）假处理对照组，共设置4个时间点。于出生后第6天，预适应组大鼠暴露于常温缺氧环境（8.0%氧气，36℃）3小时，假处理组大鼠则于36℃条件下同时暴露于常氧环境。随后将大鼠送回母鼠笼中，分别于处理后0h、2h、8h及24h这4个时间点实施安乐死。每个组别/每个时间点将使用5个脑组织样本，且每组雌雄数量均等。取出脑组织后于冰上进行解剖，分离双侧大脑皮层，并置于干冰中快速冷冻。总RNA提取采用QIAGEN RNeasy Protect Maxi试剂盒。本研究中的同窝幼鼠将接受缺氧预适应或假预适应（sham preconditioning）处理，并于24小时后施加缺氧缺血性损伤。这些大鼠将于出生后第14天实施安乐死，以进行损伤的组织病理学评估。关键词：时间进程（time-course）