Neonatal Stroke: the role of MAPK p38 and microglia

描述(申请人提供)：新生儿中风通常会导致智力低下、脑性瘫痪或癫痫。未成熟脑缺氧和缺血的损伤机制被认为与成熟脑不同，因此需要年龄合适的治疗干预。幼年动物脑缺血再灌流后驻留小胶质细胞的快速激活是再灌流损伤的机制之一。小胶质细胞的激活至少在一定程度上依赖于丝裂原激活的蛋白激酶(MAP)p38。我们假设新生儿脑再灌注损伤是由小胶质细胞通过激活MAP激酶p38介导的。我们将使用我们的新生大鼠短暂性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。具体地说，我们将确定：1)MAP激酶p38是否参与了急性损伤(目标1)；2)激活的小胶质细胞的损伤效应是由MAP激酶p38介导的(目标2)；以及3)氧化应激的药物减少小胶质细胞的激活并保护新生儿的大脑(目标3)。我们将确定MAP激酶p38的药理抑制是否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来减轻损伤，包括神经元坏死和细胞凋亡。我们将确定减轻氧化应激是否会减弱p38依赖的小胶质细胞的激活和损伤。我们使用扩散加权磁共振成像(DW-MRI)绘制缺血核心和半影区演变图的能力，将使我们能够跟踪治疗和未治疗的缺血幼鼠的损伤演变。在培养的小胶质细胞中，我们将探索p38介导的小胶质细胞激活的信号机制(目标4)，特别是调节p38、MBKK1和ASK1依赖的模块的两个信号转导级联的作用。我们将确定p38介导的小胶质细胞激活是否会加剧培养的原代神经元的缺氧损伤(目标4)。在新生儿中使用新的模型和所提出的多学科方法研究促炎途径将促进对再灌注损伤中氧化和促炎机制在新生儿卒中中的作用的认识。

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.