Omega 3 Fatty Acids Acute Neuroprotection via Mitochondria

 描述(申请人提供)：缺氧缺血性脑损伤(HI)是导致儿童永久性神经功能障碍的主要原因。Omega-3(n-3)脂肪酸(FA)，特别是二十碳五烯酸(EPA)和二十二碳六烯酸(DHA)已成为细胞膜结构+-功能的主要成分。N-3FA有益地改变了啮齿动物缺氧缺血性脑损伤的转归。研究人员的实验室证明，急性注射富含DHA和EPA的静脉注射甘油三酯(TG)乳剂对新生小鼠HI后的脑损伤具有明显的保护作用。仅含DHA的乳剂(TriDHA)显示出主要的神经保护作用，而仅含triEPA或n-6TG的乳剂不具有这种保护作用。TriDHA在再灌流后2小时仍有神经保护作用。神经保护作用与1)脑内神经保护素D1(NPD1)含量增加，2)脑线粒体DHA增加，3)线粒体膜通透性减弱有关。我们的总体假设是，TriDHA通过限制钙离子诱导的膜通透性来改变缺血后线粒体FA的组成，并保护线粒体的功能，这是缺血后细胞死亡的主要机制。我们假设的一个关键组成部分是，triDHA的有益作用与减少线粒体中的活性氧物种(ROS)激增有关，从而限制了线粒体的自氧化，从而保持了线粒体膜的完整性。这些假设将在三个具体目标下进行测试。目的1研究缺血缺氧性脑损伤后急性注射n-3TG及其分解代谢产物的特点，确定最佳剂量和FA特异性，以获得最大的神经保护作用，并与低温治疗进行比较。我们预计，注射后，triDHA首先被肝脏摄取，然后重新包装成TG或FA，和/或部分分解为NPD1，到达大脑，促进神经保护。在目标2中，我们将确定缺氧缺血后n-3TG治疗是否改变线粒体FA组成，以及这如何减轻再灌注时继发性线粒体功能障碍。我们预计这些实验将证实DHA通过减少线粒体ROS的生成来保护线粒体的主要作用，ROS是线粒体和细胞损伤的主要因素。目的3将确定DHA相关的神经保护是否与其抗凋亡作用增加NPD1的产生有关。重点将放在NPD1与线粒体相互作用以防止线粒体外膜通透的作用，以及这是否涉及抗凋亡途径的移位。

 DESCRIPTION (provided by applicant): Hypoxic-ischemic brain injury (HI) is the major cause of permanent neurological handicap in children. Omega- 3 (n-3) fatty acids (FA), especially eicosapentaenoic (EPA) and docosahexaenoic acids (DHA), have emerged as major elements for cell membrane structure+-function. n-3 FA beneficially alter outcomes of hypoxic- ischemic (HI) brain injury in rodents. The investigators' laboratories are demonstrating that acute injectio of intravenous triglyceride (TG) emulsions enriched in DHA and EPA markedly protect rodent brains against HI injury after HI in neonatal mice. Emulsions with TG containing only DHA (triDHA) showed major neuroprotective effects, and this was not shared by emulsions containing only triEPA or n-6 TG. The neuroprotection shown by triDHA occurred when injected even at 2hr after reperfusion. Neuroprotection was associated with 1) increased brain content of neuroprotectin D1 (NPD1), 2) increased DHA in cerebral mitochondria, and 3) attenuation of mitochondrial membrane permeabilization after HI. Our overall hypothesis is that triDHA changes mitochondrial FA composition and preserves mitochondrial function after HI by limiting Ca2+ induced membrane permeabilization, a central mechanism of cell death after ischemia. A key component of our hypothesis is that beneficial effects of triDHA relate to decreasing reactive oxygen species (ROS) surges in mitochondria, limiting mitochondrial self-oxidation, thereby preserving mitochondrial membrane integrity. These hypotheses will be tested under three Specific Aims. Aim 1 will characterize how n-3 TG and their catabolites are delivered to neonatal brain after acute injection following HI injury and determine optimal dosages and FA specificity for maximum neuroprotection and compare this with hypothermia treatment. We anticipate that after injection triDHA is first taken up by liver and after repackaging into TG or FA, and/or partially catabolized to NPD1 to reach brain to promote neuroprotection. In Aim 2 we will determine whether n- 3 TG treatment after HI modifies mitochondrial FA composition and how this alleviates secondary mitochondrial dysfunction in reperfusion. We expect these experiments will confirm a major role for DHA in protecting mitochondria by decreasing mitochondrial generation of ROS, a major factor for injury to mitochondria and cells. Aim 3 will determine whether DHA-associated neuroprotection relates to increased production of NPD1 through its anti-apoptotic effects. The focus will be on the role of NPD1 interacting with mitochondria to prevent permeabilization of outer mitochondrial membranes and whether this involves translocation of anti-apoptotic pathways.