AGING AND LEYDIG CELL FUNCTION

描述（由申请方提供）：Brown Norway大鼠Leydig细胞产生睾酮的最大能力随年龄增长而显著降低。我们的主要目标是阐明负责的分子机制。本申请的一个中心假设是，由Leydig细胞自身产生的活性氧（ROS）在Leydig细胞睾酮产生的年龄相关性减少中起重要作用。提出了三个具体目标。第一个是确定是否年龄相关的减少Leydig细胞睾酮生产逆转LH直接给药到老年大鼠的睾丸，或通过封装老细胞和植入到年轻的大鼠。这些研究将验证这样一个假设，即Leydig细胞外的因素可能是导致老年Leydig细胞产生睾酮能力下降的原因。在第二个具体的目标，我们将确定是否发生在Leydig细胞活性氧产生的增加，因为这些细胞的年龄是从线粒体运输链，类固醇生成的P450反应，或两者兼而有之;以及是否有年龄相关的mRNA，蛋白质和/或活性水平的主要酶活性氧清除剂在Leydig细胞-超氧化物歧化酶，谷胱甘肽过氧化物酶和过氧化氢酶。第三个目的是检查操纵活性氧负荷对Leydig细胞类固醇生成在老化过程中的影响，基于活性氧是否来自电子传递链，类固醇生成，或两者兼而有之，在老化Leydig细胞产生的睾酮减少中起着重要作用的假设。我们将测试这一假设，通过检查操纵体内氧化应激负荷对间质细胞功能的影响，包括：维生素E补充和剥夺的影响;年龄对间质细胞急性反应的影响，其主要的非酶抗氧化剂谷胱甘肽的消耗;和热量限制的影响。总之，这些研究将为Leydig细胞如何科普衰老过程中存在或增加的压力源提供新的见解，并将揭示衰老过程中Leydig细胞功能变化的潜在分子基础。

DESCRIPTION (provided by applicant): The maximal capacity of Brown Norway rat Leydig cells to produce testosterone decreases significantly with age. Our major objective is to elucidate the molecular mechanisms that are responsible. A central hypothesis of this application is that reactive oxygen species (ROS), produced by the Leydig cells themselves, play an important role in age-related reductions in Leydig cell testosterone production. Three specific aims are proposed. The first is to determine whether age-related reductions in Leydig cell testosterone production are reversed by administering LH directly to the testes of old rats, or by encapsulating old cells and implanting them into young rats. These studies will test the hypothesis that factors outside the Leydig cells might be responsible for the reduced ability of old Leydig cells to produce testosterone. In the second specific aim, we will determine whether the increases in Leydig cell reactive oxygen production that occur as these cells age are from the mitochondrial transport chain, the P450 reactions of steroidogenesis, or both; and whether there are age-related changes in mRNA, protein, and/or activity levels of the major enzymatic scavengers of reactive oxygen species in Leydig cells - SOD, glutathione peroxidase and catalase. The third aim is to examine the effects of manipulating reactive oxygen load on Leydig cell steroidogenesis during aging, based on the hypothesis that reactive oxygen, whether derived from the electron transport chain, steroidogenesis, or both, plays an important role in the reduced testosterone produced by aging Leydig cells. We will test this hypothesis by examining the consequences of manipulating oxidative stress load in vivo on Leydig cell function, including: the effects of vitamin E supplementation and deprivation; the effects of age on the acute response of Leydig cells to depletion of its major non-enzymatic antioxidant, glutathione; and the effects of caloric restriction. Together, these studies will provide new insights into how Leydig cells cope with stressors that are present or increase during aging, and will shed light on the underlying molecular basis for functional changes in Leydig cells that occur during aging.