Omega 3 Fatty Acids Acute Neuroprotection via Mitochondria

 描述（由申请人提供）：缺氧缺血性脑损伤（HI）是儿童永久性神经障碍的主要原因。ω-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+功能的主要元素。n-3FA有益地改变啮齿动物缺氧缺血性（HI）脑损伤的结果。研究者的实验室正在证明，急性静脉注射富含DHA和EPA的甘油三酯（TG）乳剂可显著保护新生小鼠HI后啮齿动物脑免受HI损伤。仅含DHA（triDHA）的TG乳剂显示出主要的神经保护作用，而仅含triEPA或n-6 TG的乳剂不具有这种作用。即使在再灌注后2小时注射triDHA也显示出神经保护作用。神经保护作用与1）脑内神经保护素D1（NPD 1）含量增加，2）脑线粒体中DHA含量增加和3）HI后线粒体膜透性减弱有关。我们的总体假设是，triDHA改变线粒体FA组成和保护线粒体功能后HI限制Ca 2+诱导的膜透化，缺血后细胞死亡的中心机制。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（ROS）激增有关，限制线粒体自氧化，从而保持线粒体膜的完整性。这些假设将在三个具体目标下进行检验。目的1将表征HI损伤后急性注射n-3 TG及其催化剂如何递送至新生儿脑，并确定最大神经保护的最佳剂量和FA特异性，并将其与低温治疗进行比较。我们预计，注射后，triDHA首先被肝脏吸收，然后重新包装成TG或FA，和/或部分分解代谢成NPD 1，到达大脑，促进神经保护。在目的2中，我们将确定HI后n- 3 TG治疗是否改变线粒体FA组成，以及这如何减轻再灌注中的继发性线粒体功能障碍。我们希望这些实验将证实DHA通过减少线粒体产生ROS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通过其抗凋亡作用增加NPD 1的产生有关。重点将是NPD 1与线粒体相互作用，以防止线粒体外膜的透化，以及这是否涉及抗凋亡途径的易位的作用。

 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.