Targeting Antioxidant Therapy to Cardiac Mitochondria

描述（由申请人提供）： 糖尿病与心脏功能障碍有关，部分原因是底物利用和线粒体功能障碍的变化。我们最近发现，线粒体ROS过度生产损害心肌能量在糖尿病啮齿动物的心脏。这项探索性和开发性R21提案的目的是测试直接心肌给药各种抗氧化剂制剂以减少心肌ROS过度产生和恢复心肌生物能量学的功效。我们将利用一种新的聚合物为基础的药物输送系统，可以直接滴注到小鼠的心包囊。该聚合物在室温下是水性的，但在体温下形成稳定的凝胶，并允许在30天内将化合物直接持续递送至心脏，而不改变体内血液动力学。除了持续递送之外，该方法还具有能够以高局部浓度施用相对不溶性、不稳定或昂贵的物质而没有潜在的有害全身作用的优点。拟议的研究将检验以下假设。(1)在严重2型糖尿病小鼠模型db/db小鼠中，将有效的细胞渗透性SOD模拟物（MnTBAP）直接心肌给药至心肌将减少ROS产生并增强线粒体能量学。(2)通过TPP缀合天然存在的抗氧化剂（维生素E、辅酶Q和类黄酮槲皮素）的线粒体靶向将增强它们在减少糖尿病心脏中心肌线粒体ROS产生方面的功效。(3)天然存在的抗氧化剂（抗坏血酸或α-生育酚）与二氢-α-硫辛酸的组合在减少糖尿病心脏中线粒体ROS过度产生方面比单独的单一药剂具有增加的功效。将在给予抗氧化剂化合物后10天测定线粒体超氧化物和过氧化氢产生以及氧消耗和ATP产生。该方法提供了一种新颖且具有成本效益的手段，以直接且快速地筛选大量潜在的药剂，用于降低体内心脏线粒体中线粒体超氧化物过量产生的功效。一旦确定了有效性，就可以在全身给药后对有希望的试剂进行药代动力学和毒理学分析。

DESCRIPTION (provided by applicant): Diabetes is associated with cardiac dysfunction, due in part to changes in substrate utilization and mitochondrial dysfunction. We have recently found that mitochondrial ROS overproduction impairs myocardial energetics in the hearts of diabetic rodents. The goal of this exploratory and developmental R21 proposal is to test the efficacy of direct myocardial administration of various anti-oxidants preparations to reduce myocardial ROS overproduction and restore myocardial bioenergetics. We will utilize a novel polymer based drug delivery system that can be directly instilled into the pericardial sac of mice. The polymer is aqueous at room temperature but forms a stable gel at body temperature and allows for sustained delivery of compounds directly to the heart over 30 days, without altering in vivo hemodynamics. In addition to sustained delivery, this approach has the advantage of enabling the administration of relatively insoluble, unstable or expensive substances at high local concentration without the potential of deleterious systemic effects. The proposed studies will test the following hypothesis.(1) That direct myocardial administration of a potent cell-permeable SOD mimetic (MnTBAP) to the myocardium will reduce ROS production and enhance mitochondrial energetics in a mouse model of severe type 2 diabetes the db/db mouse. (2) That mitochondrial targeting of naturally occurring anti-oxidants (Vitamin E, Coenzyme Q and the flavonoid Quercetin) via TPP conjugation will enhance their efficacy in reducing myocardial mitochondrial ROS generation in diabetic hearts. (3) That a combination of naturally occurring antioxidants (ascorbic acid or alpha-tocopherol) with dihydro-alpha lipoic acid will have increased efficacy in reducing mitochondrial ROS overproduction in diabetic hearts than single agents alone. Mitochondrial superoxide and hydrogen peroxide generation, as well as oxygen consumption and ATP production will be determined ten-days following the administration of anti-oxidant compounds. This approach provides a novel and cost effective means to directly and rapidly screen a large number of potential agents for efficacy in reducing mitochondrial superoxide overproduction in cardiac mitochondria in vivo. Once efficacy is determined, promising reagents can then be subjected to pharmacokinetic and toxicological analysis following systemic administration.