THE EFFECTS OF CYCLIC TESTOSTERONE ADMINISTRATION ON MUSCLE FUNCTION IN OLDER

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。无论男性和女性的体力活动水平如何，随着年龄的增长，他们的瘦肌肉量（肌肉减少症）都会逐渐减少。雄激素刺激男性的骨骼肌群。肌肉质量的增加是通过改善净蛋白质平衡来实现的，这是由肌肉蛋白质合成的增加或肌肉蛋白质分解的抑制所决定的。循环使用睾酮可以提供更持续的肌肉力量增加，同时减少暴露于雄激素，这将限制长期暴露的潜在副作用。本研究的目的是：1)确定连续和循环给药睾酮对肌肉肌原纤维和线粒体蛋白合成的影响，2)确定循环和连续给药睾酮对骨骼肌单纤维功能的影响，3)确定循环和连续给药睾酮对骨骼肌单纤维功能的影响。研究对象为65-85岁的正常健康老年男性。该临床方案旨在比较三组老年男性的具体结果：安慰剂组，每周接受肌内注射睾酮酸（TE， 100毫克）5个月，每周接受TE治疗1个月，每周交替接受安慰剂注射1个月，共5个月

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Men and women undergo a progressive reduction in lean muscle mass (sarcopenia) with advancing age regardless of their level of physical activity. Androgen stimulates skeletal muscle mass in men. This increase in muscle mass occurs through an improvement in net protein balance- determined by either an increase in muscle protein synthesis or an inhibition of muscle protein breakdown. Cycling testosterone could provide a more consistent increase in muscle strength while reducing the exposure to androgens that would limit potential side effects from long term exposure. The aims of this study are to: 1) determine the effect of continuous and cycled testosterone administration on muscle myofibrillar and mitochondrial protein synthesis, 2) determine the effect of cycled and continuous testosterone administration on skeletal muscle single fiber function, and 3) determine the effect of cycled and continuous testosterone administration on skeletal muscle single fiber function. Normal healthy older men ages 65-85 will be studied. This clinical protocol is designed to compare specific outcomes in older men between three groups- placebo, men receiving testosterone enanthate (TE, 100 mg) weekly by intramuscular injection for 5 months, and men receiving TE weekly for 1 month alternating with weekly placebo injections for 1 month for a total of 5 month