CDP-choline: Mechanisms in Cerebral Ischemia

CDP-胆碱：脑缺血的机制

• 批准号: 7060785
• 负责人: RAO M ADIBHATLA
• 金额: $ 27万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-05-01 至 2008-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7060785
• 关键词: arachidonate; cardiolipins; cerebral ischemia /hypoxia; choline; cytosine nucleotides; enzyme activity; enzyme mechanism; gerbil /jird; glutathione; histopathology; immunocytochemistry; pharmacokinetics; phosphatidylcholines; phosphodiesterases; phospholipase A2; phospholipids; reperfusion; sphingomyelin phosphodiesterase; sphingomyelins; spontaneous hypertensive rat; western blottings

DESCRIPTION (provided by applicant): Significance and goal: CDP-choline (citicoline) stroke clinical trials in Europe and Japan showed significant improvement, while US studies provided ambiguous results. The route of administration (oral in USA vs iv in non-USA) and 24-hr time window may have hindered its effectiveness in the USA trials. It has now been realized that oral administration in USA trials was inappropriate and new Phase III trials will soon be undertaken. Our studies show that CDP-choline treatment delayed by 3-hr did not offer any neuroprotection. CDP-choline mode of action has not been clearly identified, and understanding its mechanism(s) should lead to more effective treatment of ischemic brain injury. The efficacy of CDP-choline in stroke therapy might still be achieved. Rationale: Phospholipid degradation is a significant promoter of neuronal death after transient cerebral ischemia. CDP-choline neuroprotection is thought to be due to increased phosphatidyl-choline (PtdCho) synthesis in the injured brain, although the evidence is limited. We showed in gerbil transient forebrain ischemia that CDP-choline: (a) provided significant neuroprotection (b) significantly restored PtdCho, cardioliPin and sphingomyelin, (c) attenuated arachidonic acid release and metabolism, and (d) increased glutathione levels. Our preliminary results show that CDP-choline affects activation of membrane and mitochondrial phospholipase A2 (PLA2) that is raM-Ca 2+ dependent (characteristic of secretory PLA2; sPLA2), supporting the hypothesis and Aim 1. In vitro, CDP-choline and its components (cytidine and choline) did not inhibit PLA2 activity, and thus as such CDP-choline is not a "direct PLA2 inhibitor". Instead CDP-choline in vivo likely affects PLA2 activation. Hypothesis: CDP-choline attenuates phospholipid hydrolysis by preventing activation of PLA2. To test this hypothesis in transient cerebral ischemia, we propose the following specific aims: Aim 1: Determine whether CDP-choline inhibits PLA2 activation and protein expression. Since this aim is central to our hypothesis, it will be tested both in gerbil transient forebrain ischemia and transient focal cerebral ischemia of spontaneously hypertensive rat. Aim 2: Determine whether CDP-choline alters cytidine triphosphate phosphocholine cytidylyltransferase (PCCT) and sphingomyelinase activities mediated through PLA2. PCCT makes endogenous CDP-choline and is the rate-limiting enzyme in PtdCho synthesis. Exogenous CDP-choline is hydrolyzed, absorbed as cytidine and choline, and has to be re-synthesized by PCCT. PtdCho hydrolysis by PLA2 results in lyso-PtdCho and arachidonic acid. Lyso-PtdCho inhibits PCCT activity resulting in impaired PtdCho synthesis. Arachidonic acid activates neutral sphingomyelinase, resulting in membrane disintegration. PCCT activity was stimulated by exogenous CDP-choline. Aim 2 will be tested in gerbil transient forebrain ischemia.

描述(由申请人提供)：意义和目标：在欧洲和日本的CDP-胆碱(胞二磷胆碱)中风临床试验显示有显著改善，而美国的研究提供了不明确的结果。给药途径(在美国口服与在非美国静脉注射)和24小时时间窗口可能阻碍了其在美国试验中的有效性。现在已经意识到在美国的试验中口服给药是不合适的，即将进行新的第三阶段试验。我们的研究表明，延迟3小时的CDP-胆碱治疗没有提供任何神经保护作用。顺铂-胆碱的作用模式尚未明确，了解其作用机制(S)应有助于更有效地治疗缺血性脑损伤。CDP-胆碱在卒中治疗中的疗效仍有可能达到。 原理：磷脂降解是短暂性脑缺血后神经元死亡的重要促进因素。CDP-胆碱的神经保护作用被认为是由于损伤大脑中磷脂酰胆碱(PtdCho)合成的增加，尽管证据有限。我们在沙土鼠短暂性前脑缺血中发现：(A)CDP-胆碱提供了显著的神经保护作用，(B)显著恢复了PtdCho、心磷脂和鞘磷脂，(C)抑制了花生四烯酸的释放和代谢，(D)提高了谷胱甘肽水平。我们的初步结果表明，CDP-胆碱影响膜和线粒体磷脂酶A2(PLA2)的激活，这种激活依赖于Ram-Ca~(2+)(分泌型PLA2；sPLA2)，支持假设和目的1。在体外，CDP-胆碱及其成分(胞苷和胆碱)不抑制PLA2的活性，因此CDP-胆碱不是“直接的PLA2抑制物”。相反，体内的CDP-胆碱可能会影响PLA2的激活。 假设：CDP-胆碱通过阻止PLA2的激活来减弱磷脂的水解。为了在短暂性脑缺血中验证这一假说，我们提出了以下具体目标：目的1：确定CDP-胆碱是否抑制PLA2的激活和蛋白表达。由于这一目标是我们假设的中心，它将在沙土鼠短暂性前脑缺血和自发性高血压大鼠的短暂性局灶性脑缺血中进行测试。目的：研究CDP-胆碱是否通过磷脂酶A2改变胞苷三磷酸、磷酸胆碱胞苷转移酶(PCCT)和鞘磷脂酶的活性。PCCT产生内源性CDP-胆碱，是PtdCho合成的限速酶。外源CDP-胆碱被降解，以胞苷和胆碱的形式被吸收，需要通过PCCT重新合成。PtdCho被PLA2水解生成Lyso-PtdCho和花生四烯酸。Lyso-PtdCho抑制PCCT活性，导致PtdCho合成受损。花生四烯酸激活中性鞘磷脂酶，导致膜解体。外源性CDP-胆碱刺激PCCT活性。目的2将在沙土鼠短暂性前脑缺血中进行试验。

项目成果

Phospholipase A(2), reactive oxygen species, and lipid peroxidation in CNS pathologies.

• DOI: 10.5483/bmbrep.2008.41.8.560
• 发表时间: 2008-08-31
• 期刊: BMB reports
• 影响因子: 3.8
• 作者: Adibhatla RM;Hatcher JF
• 通讯作者: Hatcher JF