THE EFFECTS OF CYCLIC TESTOSTERONE ADMINISTRATION ON MUSCLE FUNCTION IN OLDER

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 男性和女性随着年龄的增长，无论他们的体力活动水平如何，都会经历精瘦肌肉质量(骨骼肌减少)的逐渐减少。雄激素刺激男性的骨骼肌群。这种肌肉质量的增加是通过改善净蛋白质平衡来实现的--这取决于肌肉蛋白质合成的增加或肌肉蛋白质分解的抑制。循环使用睾丸素可以更稳定地增加肌肉力量，同时减少雄激素的暴露，从而限制长期暴露的潜在副作用。本研究的目的是：1)确定睾酮连续和连续给药对肌原纤维和线粒体蛋白质合成的影响；2)确定睾酮循环和连续给药对骨骼肌单纤维功能的影响；3)确定睾酮循环和连续给药对骨骼肌单纤维功能的影响。将对年龄在65-85岁的正常健康老年男性进行研究。这一临床方案旨在比较三组老年男性的具体结果--安慰剂组、每周肌肉注射睾丸酮(TE)100毫克、为期5个月的男性，以及每周接受TE、每周交替注射安慰剂1个月、总共5个月的男性。 另一个小组开始接受为期一周、休息一周的TE，但由于资金限制，无法研究原计划之外的其他主题，因此停止了这项工作。

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 months. An additional group receiving TE on a week-on, week-off basis was initiated , however this was halted due to financial constraints that would not allow the study of additional subjects beyond those originally planned.