Neonatal Stroke: the role of MAPK p38 and microglia

描述（由申请人提供）：新生儿中风通常会导致智力迟钝、脑瘫或癫痫。未成熟脑中缺氧和缺血的损伤机制被认为与成熟脑中的损伤机制不同，因此需要与年龄相适应的治疗干预。未成熟动物脑缺血后再灌注时驻留小胶质细胞的快速激活是再灌注损伤传播的机制之一。小胶质细胞的活化至少部分取决于促分裂原活化蛋白激酶（MAP激酶）p38。我们推测，新生儿脑再灌注损伤是通过激活MAP激酶p38介导的小胶质细胞活化。我们将使用我们的新生大鼠短暂局灶性脑缺血再灌注模型来探讨MAP激酶p38在神经保护中的作用。具体而言，我们将确定：1）MAP激酶p38是否有助于急性损伤（目的1）; 2）激活的小胶质细胞的损伤作用是由MAP激酶p38介导的（目的2）; 3）药理学减少氧化应激减弱小胶质细胞活化并保护新生儿大脑（目的3）。我们将确定是否药理学抑制MAP激酶p38减弱损伤，神经元坏死和凋亡，通过减少激活的小胶质细胞中细胞因子和一氧化氮的产生的幅度。我们将确定是否减轻氧化应激减弱p38依赖的激活小胶质细胞和损伤。我们能够使用弥散加权磁共振成像（DW-MRI）绘制不断发展的缺血核心和半暗带，这将使我们能够跟踪治疗和未治疗的缺血性幼崽的损伤演变。在培养的小胶质细胞中，我们将探索p38介导的小胶质细胞活化的信号传导机制（目的4），特别是调节p38，MBKK 1和ASK 1依赖模块的两个信号转导级联的贡献。我们将确定p38介导的小胶质细胞活化是否加重培养的原代神经元的缺氧损伤（目的4）。在新生儿中使用新模型和所提出的多学科方法研究促炎通路将促进对新生儿卒中中再灌注损伤的氧化和促炎机制的作用的认识。

DESCRIPTION (provided by applicant): Neonatal stroke often leads to mental retardation, cerebral palsy, or epilepsy. The injurious mechanisms of hypoxia and ischemia in immature brain are thought to differ from those in mature brain, therefore requiring age-appropriate therapeutic interventions. Rapid activation of resident microglia upon reperfusion following cerebral ischemia in immature animals is one of the mechanisms that propagate reperfusion injury. Activation of microglia at least in part depends on the mitogen-activated protein kinase (MAP kinase) p38. We hypothesize that reperfusion injury in the neonatal brain is mediated by microglial activation via activation of MAP kinase p38. We will use our transient focal ischemia-reperfusion model in neonatal rats to explore the role of MAP kinase p38 in neuroprotection. Specifically, we will determine whether: 1) MAP kinase p38 contributes to the acute injury (Aim 1); 2) injurious effects of activated microglia are mediated by MAP kinase p38 (Aim 2); and 3) pharmacological reduction of oxidative stress attenuates microglial activation and protects the neonatal brain (Aim 3). We will determine whether pharmacological inhibition of MAP kinase p38 attenuates injury, both neuronal necrosis and apoptosis, by decreasing the magnitude of cytokine and nitric oxide production in activated microglia. We will determine whether lessening the oxidative stress attenuates p38-dependent activation of microglia and injury. Our ability to map the evolving ischemic core and penumbra using diffusion-weighted magnetic resonance imaging (DW-MRI) will allow us to follow injury evolution in treated and non-treated ischemic pups. In cultured microglia, we will explore signaling mechanisms of p38-mediated activation of microglia (Aim 4), in particular, the contribution of two signal transduction cascades that regulate p38, MBKK1- and ASK1-dependent modules. We will determine whether p38-mediated microglial activation exacerbates hypoxic injury to cultured primary neurons (Aim 4). The study of a pro-inflammatory pathway using a new model in the neonate and the proposed multidisciplinary approach will advance knowledge about the role of oxidative and pro-inflammatory mechanisms of reperfusion injury in neonatal stroke.