Prevention of age-associated musculoskeletal loss by n-3 fatty acids

说明(申请人提供)：衰老与炎症和氧化应激增加有关，导致肌肉骨骼组织质量、质量和功能的进行性下降，从而增加老年人跌倒和骨折的风险。N-3脂肪酸(FA)和卡路里限制(CR)都是抗炎和抗氧化的。CR改善肌肉质量、质量和功能，n-3 FA改善骨密度(BMD)和肌肉功能，防止骨质流失。我们观察到n-3FA喂养的小鼠后腿瘦肉质量增加。然而，40%的CR与骨丢失增加有关。因此，我建议研究n-3FA和轻度CR(20%CR)在预防年龄相关性肌肉骨骼丢失中的联合作用。我推测轻度CR会有非常少的饮食限制相关的骨丢失。肌肉和骨骼是肌肉骨骼系统中同一功能单元的两个部分。为了确定n-3FA+轻度CR对衰老过程中肌肉健康的有益影响，我将进行双能量吸收法(DXA)来测定肌肉质量；分析肌肉的纤维类型、脂肪含量、铁含量、抗氧化酶和氧化损伤水平以确定肌肉质量；通过测量活性氧和ATP产生、膜电位、呼吸频率和电子传递复合体的活性来分析线粒体功能，以确定肌肉活动；分析握力和跑步机耐力以确定肌肉力量。我预计n-3FA+轻度CR将通过保持肌肉纤维数量、减少脂肪和铁的积累以及氧化还原平衡来防止肌肉质量、质量和功能的老化下降，从而保持适当的线粒体功能以提供足够的能量。为了确定在老化过程中添加或不添加轻度CR的n-3FA对骨健康的有利作用，我将进行DXA测量骨量；通过核磁共振分析骨孔率、孔洞大小分布以及可移动水和结合水的比例来确定骨质量；分析骨形成和骨吸收活动以确定骨重建状态；分析股骨材料试验和椎骨生物力学试验以确定骨强度和抗骨折韧性。我预计，无论有无轻度CR动物，n-3FA的骨质量将得到保持，这是由于骨形成和吸收细胞的平衡活动导致更高的骨密度、更少的骨孔率和更好的骨结合水，从而提高骨质量和强度，降低骨脆性和相关骨折。最近，人类和动物研究表明，使用10-30%的CR具有一定的保护作用，包括改善肌肉功能。然而，轻度CR预计只能在中位寿命提供益处，但可能不会导致40%的CR的最长寿命。我们观察到饲喂n-3FA+40%CR的小鼠存活时间延长。如果在n-3FA存在的情况下，轻度CR可以延长与40%CR相似的寿命，这是很有意义的。我还将确定n-3FA+轻度CR介导的健康衰老和延长寿命是否与炎症和氧化应激相关基因的减少有关。这项建议将确立n-3FA和轻度CR对与年龄相关的肌肉骨骼丢失的丙乳酸功效，从而确保健康衰老和延长寿命。我的直接职业目标是在导师和顾问的指导下获得足够的额外技能和知识，成为衰老和与衰老相关的肌肉骨骼生物学领域的独立研究人员，并产生足够的初步数据来申请独立的R01拨款。我的长期职业目标是通过在老龄化领域进行持续的基础和转化性研究，将自己确立为一名富有成效的、由赠款资助的独立研究员。我想制定饮食预防和治疗策略，以预防/治疗与年龄相关的肌肉骨骼健康恶化。在成功的动物研究后，我的最终目标是继续进行临床试验，以建立这些策略，以改善人类在衰老期间的健康。我的研究生涯发展计划的关键要素是：(1)通过参加教学课程和密集的指导互动，获得与老龄化领域相关的新技术/高级基础和临床知识的教育/培训(2)获得拨款撰写方面的具体培训(3)生成足够的初步数据以支持竞争性的R01拨款申请(4)提交拨款提案(5)在国内和国际会议上展示我的工作(6)发表同行评议的论文(7)参加会议和期刊俱乐部以及(8)与我研究领域的杰出科学家建立强大的网络。我的研究所提供了一个极好的场所，拥有非常深入的专业知识和资源，这些资源高度支持我的科学项目，以及我的职业发展计划。我的整个职业发展将由一个咨询委员会监督，该委员会由炎症、氧化应激、肌肉生物学、骨骼生物学和衰老领域的国内和国际知名科学家组成。

DESCRIPTION (provided by applicant): Aging is associated with increased inflammation and oxidative stress leading to progressive decline in musculoskeletal tissue mass, quality and function which increases the risk of falls and fractures in the elderly. Both n-3 fatty acids (FA) and calorie restriction (CR) are anti-inflammatory and anti-oxidative. CR improves muscle mass, quality and function and n-3 FA improves bone mineral density (BMD) and muscle function and prevents bone loss. We observed increased hind leg lean mass in n-3 FA fed mice. However, 40% CR is associated with increased bone loss. Therefore, I proposed to study the combined effect of n-3 FA and mild CR (20% CR) in preventing age-associated musculoskeletal loss. I speculate that mild CR will have very minimal dietary restriction associated bone loss. The muscles and bones act as two parts of the same functional unit of the musculoskeletal system. To determine the beneficial effect of n-3 FA+ mild CR on muscle health during aging, I will perform dual energy absorptiometry (DXA) to determine muscle mass; analyze fiber types, fat content, iron content, antioxidant enzymes and oxidative damage levels of muscle to determine muscle quality; analyze mitochondrial functions by measuring reactive oxygen species and ATP production, membrane potential, respiratory rates, and electron transport complex activities to determine muscle activity; analyze grip strength and treadmill endurance capacity to determine muscle strength. I anticipate that n-3 FA+ mild CR will prevent aging related decline in muscle mass, quality and function by maintaining muscle fiber numbers with reduced fat and iron accumulation and redox balance, thereby maintaining proper mitochondrial functions to provide sufficient energy. To determine the beneficial effect of n-3 FA with/without mild CR on bone health during aging, I will perform DXA to determine bone mass; analyze bone porosity, pore size distribution and fractions of mobile and bound water by nuclear magnetic resonance (NMR) to determine bone quality; analyze bone formation and bone resorption activities to determine bone remodeling status; analyze material testing of femur and biomechanical tests of vertebrae to determine bone strength and toughness against bone fracture. I anticipate that bone quality of n-3 FA with/without mild CR animals will be maintained due to balanced activities of bone forming and resorbing cells leading to superior BMD, less bone porosity, and better bone bound water, thereby improving bone quality and strength and reducing bone fragility and associated fractures. Recently, human and animal studies were carried out using 10-30% CR and showed certain protective effects including muscle function improvement. However, mild CR is expected to provide benefits only at median lifespan but may not cause a maximal lifespan as of 40% CR. We observed extended survival of mice fed n-3 FA+40% CR. It is of interest if mild CR in the presence of n-3 FA can extend the life span similar to that of 40% CR. I will also determine whether n-3 FA+ mild CR mediated healthy aging and prolongation of life is associated with reduction of genes related to inflammation and oxidative stress. This proposal will establish the prophaylactic efficacy of n-3 FA and mild CR against age-associated musculoskeletal loss, thereby ensuring healthy aging and prolongation of lifespan. My immediate career goal is to gain sufficient additional skills and knowledge necessary to be an independent researcher in the field of aging and aging-associated musculoskeletal biology under the guidance of mentors and advisors and generate sufficient preliminary data to apply for independent R01 grants. My long term career goal is to establish myself as a productive, grant-funded, independent investigator through sustained basic and translational research in the area of aging. I would like to develop dietary prophylactic and therapeutic strategies to prevent/treat age-associated deterioration of musculoskeletal health. After successful animal study, my ultimate goal is to pursue clinical trials to establish these strategies to improve human health during aging. The key elements of my research career development plan are: (1) gain education/training on new technologies/advanced basic and clinical knowledge relevant to the field of aging by taking didactic courses and intensive mentoring interactions (2) acquire specific training in grant writing (3) generate sufficient preliminary data to support competitive R01 grant application (4) submit grant proposals (5) present my work at national and international conferences (6) publish peer-reviewed papers (7) attend conferences and journal clubs and (8) establish a strong network with prominent scientists in the field of my research. My institute provides an excellent venue that has a remarkable depth of expertise and resources that are highly supportive of my scientific project, as well as my career development plans. My overall career development will be monitored by an advisory committee consists of nationally and internationally reputed scientists in the field of inflammation, oxidative stress, muscle biology, bone biology and aging.