Effects of Cocoa Flavonols on Myocardial Infarction Size and Post-Injury Injury

描述（由申请人提供）：本提案的主要目的是表征可可和黄烷醇、表儿茶素减少大鼠短期和长期缺血-再灌注诱导的心肌损伤的能力。此外，我们希望提供证据证明可可和表儿茶素通过一氧化氮（NO）依赖性机制减少嗜热链球菌介导的心肌缺血再灌注（IR）损伤的能力。多酚广泛分布于植物中，被称为类黄酮。 有证据表明，食用富含类黄酮的食物与心血管（CVD）疾病的发病率呈负相关。可可粉中黄烷醇（儿茶素和表儿茶素）的含量大于10重量%。对黄酮醇有益作用的兴趣来自对库纳印第安人的观察，他们的心血管疾病发病率非常低，消费最低限度加工的可可饮料。有一些线索可以解释可可的作用机制。食用富含黄烷醇的可可会导致血管舒张，这可以通过使用NO合成抑制剂来逆转。其他有益作用包括抑制血小板和白细胞粘附、低密度脂蛋白氧化、活性氧（ROS）产生、类花生酸合成和胰岛素抵抗。最近的报告将可可的有益效果与表儿茶素的作用联系起来。人类食用表儿茶素可以复制可可的血管扩张作用以及其抗氧化和胰岛素增敏作用。血管舒张作用可以通过在离体血管制备物上使用表儿茶素代谢物来复制。在大鼠心肌IR损伤模型中进行的初步研究表明表儿茶素可以发挥心脏保护作用。治疗还可以减少心肌炎症。 有趣的是，损伤似乎需要血细胞的存在。 考虑到可可衍生的黄烷醇对心血管参数的有益作用，这些化合物可能显著减少组织损伤并最终改善长期器官结构/功能。需要血液来介导组织损伤也表明中性粒细胞的参与。考虑到这些问题，我们建议检查以下具体目标：目标1将测试的假设，可可或表儿茶素给药大鼠导致心肌IR损伤的减少，并改善长期的结果。大鼠将经受45分钟的IR损伤。将在IR后4周内确定心肌梗死的大小以及心肌损伤诱导的心脏结构/功能变化。将确定ROS产生、NO产生和抗炎终点。研究将包括使用剂量反应方案和血浆输注来测试保护的“可转移性”。目的2将测试可可或表儿茶素处理降低体内PMN粘附/捕获以及其活化状态的假设。目的3将测试可可或表儿茶素诱导的一氧化氮增加调节（至少部分）黄烷醇对PMN的抗粘附作用的假设。 公共卫生相关性：该提案的主要目标是表征可可衍生的黄烷醇特别是表儿茶素的能力，以减少短期和长期缺血-再灌注诱导的心脏损伤，并确定炎症细胞所起的作用。鉴于对黑巧克力相关黄烷醇的影响的关注，我们因此解决了与补充和替代医学领域相关的主题。

DESCRIPTION (provided by applicant): The major objective of this proposal is to characterize the ability of cocoa and the flavanol, epicatechin, to reduce short and long-term ischemia-reperfusion induced myocardial injury in rats. Furthermore, we wish to provide evidence for the ability of cocoa and epicatechin to reduce neutrophil-mediated myocardial ischemia-reperfusion (IR) injury via a nitric oxide (NO) dependent mechanism. Polyphenols are widely distributed in plants and are known as flavonoids. Evidence indicates a negative correlation between consumption of flavonoid-rich foods and incidence of cardiovascular (CVD) disease. Cocoa powder is more than 10% flavanols (catechin and epicatechin) by weight. Interest in the beneficial effects of flavonols emerged from observations in Kuna Indians who have a very low incidence of CVD and consume minimally processed cocoa beverages. There are clues as to the mechanisms that explain cocoa effects. The consumption of flavanol rich cocoa leads to vasodilation which can be reversed by the use of an NO synthesis inhibitor. Other beneficial effects include the inhibition of platelet and leucocyte adhesion, low-density lipoprotein oxidation, reactive oxygen species (ROS) generation, eicosanoid synthesis and insulin resistance. Recent reports associate the beneficial effects of cocoa to the actions of epicatechin. The consumption of epicatechin by humans reproduces the vasodilatory effects of cocoa as well as its antioxidant and insulin sensitizing actions. Vasodilatory effects can be replicated by the use of epicatechin metabolites on isolated blood vessel preparations. Preliminary studies performed in a rat model of myocardial IR injury indicate epicatechin can exert cardioprotective effects. Treatment also reduces myocardial inflammation. Interestingly injury appears to require the presence of blood borne cells. Given the well documented beneficial effects of cocoa derived flavanols on cardiovascular parameters it is possible that these compounds may significantly reduce tissue injury and ultimately, improve long term organ structure/function. The requirement of blood to mediate tissue injury also suggests the involvement of neutrophils. With these issues in mind we propose to examine the following specific aims: Aim 1 will test the hypothesis that the administration of cocoa or epicatechin to rats leads to a reduction in myocardial IR injury and improves long term outcome. Rats will be subjected to 45 min of IR injury. Infarct size as well as myocardial injury-induced changes in cardiac structure/function will be determined up to 4 weeks post IR. ROS generation, NO production and anti-inflammatory endpoints will be determined. Studies will include the use of dose-response schemes and plasma transfusions to test for the "transferability" of protection. Aim 2 will test the hypothesis that cocoa or epicatechin treatment reduces in vivo PMN adhesion/trapping as well as their activation state. Aim 3 will test the hypothesis that cocoa or epicatechin induced increases in nitric oxide modulate (at least in part) the anti-adhesive effects of flavanols on PMN. PUBLIC HEALTH RELEVANCE: The major goal of this proposal is to characterize the ability of cocoa derived flavanols specifically epicatechin, to reduce short and long-term ischemia-reperfusion induced heart injury and to identify the role played by inflammatory cells. Given the focus on the effects of dark chocolate related flavanols we therefore address a topic relevant to the field of complementary and alternative medicine.