THE EFFECTS OF CYCLIC TESTOSTERONE ADMINISTRATION ON MUSCLE FUNCTION IN OLDER

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。无论男性和女性的身体活动水平如何，随着年龄的增长，瘦肌肉质量（肌肉减少症）都会逐渐减少。雄激素刺激男性骨骼肌质量。这种肌肉质量的增加是通过净蛋白质平衡的改善而发生的-通过增加肌肉蛋白质合成或抑制肌肉蛋白质分解来确定。循环睾酮可以提供更一致的肌肉力量增加，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）确定连续和循环睾酮给药对肌肉肌原纤维和线粒体蛋白合成的影响，2）确定循环和连续睾酮给药对骨骼肌单纤维功能的影响，3）确定循环和连续睾酮给药对骨骼肌单纤维功能的影响。 将研究65-85岁的正常健康老年男性。本临床方案旨在比较三组老年男性的具体结果-安慰剂组、每周肌肉注射庚酸睾酮（TE，100 mg）5个月的男性和每周接受TE 1个月与每周安慰剂注射1个月交替共5个月的男性

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