DOSE-RESPONSE OF SEX STEROIDS ON BONE METABOLISM IN MEN (SEE SPID 0665)

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。 将男性的睾丸素降低到青春期前的水平会对身体的许多功能产生不利影响。具体地说，睾酮水平非常低的男性会经历骨质流失、肌肉力量下降、肌肉尺寸缩小、脂肪质量增加、性冲动降低，总体上感觉不如正常男性。随着男性年龄的增长，睾酮水平逐渐下降(尽管很少会变得非常低)，男性往往会经历与睾酮相关的功能变化。尽管如此，睾丸激素的自然减少在多大程度上可能是这些不利影响的原因尚不清楚。这项研究的目标是确定这些变化开始发生时的睾丸素水平。 这项研究将招募200名年龄在20-50岁之间的健康男性。受试者将每4周注射一次，可逆地将他们的睾丸激素降低到青春期前的水平。(请注意，当注射停止时，睾酮水平立即恢复正常)。每个受试者还被给予受试者一定数量的替代睾丸素凝胶。有5种可能的替代睾酮剂量，旨在产生从非常低到正常的血液睾丸素水平。给每个病人的剂量是随机确定的。在16周的过程中，将跟踪一系列指标，包括骨骼分解、肌肉大小和力量、脂肪质量、性冲动、能量水平和情绪水平。通过将这些剂量-反应关系与SPID 0665的剂量-反应关系进行比较，我们将能够评估雌激素在男性关键生理功能中所起的作用。

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. Lowering testosterone in men to pre-pubertal levels causes adverse effects on many body functions. Specifically, men with very low testosterone levels experience bone loss, decreased muscle strength, decreased muscle size, increased fat mass, lower sexual drive, and generally feel less well than normal men. As men age, testosterone levels decline gradually (though they rarely become extremely low) and men often experience changes in testosterone-related functions. Still, the degree to which the natural reduction of testosterone may be responsible for these adverse effects is unknown. The goal of this study is to determine the level of testosterone at which these changes begins to occur. This study will enroll 200 healthy men ages 20-50. Subjects will be given an injection every 4 weeks that reversible lowers their testosterone to pre-pubertal levels. (Note that when the injections are stopped, testosterone levels return promptly to normal). Each subject is also given a controlled amount of replacement testosterone gel. There are 5 possible doses of replacement testosterone that are designed to produce blood testosterone levels that range from very low to normal. The dose given to each patient is randomly determined. Over the course of 16 weeks a number of measures will be tracked including bone breakdown, muscle size and strength, fat mass, sexual drive, energy levels, and mood levels. By comparing these dose-response relationships with those from SPID 0665 we will be able to assess the role that estrogen plays in key physiologic functions in men.