Aging and Leydig Cell Function

在这项优点扩展申请中提出的研究解决了通过 增龄对睾丸雄激素分泌细胞间质细胞微环境的影响 生物合成，导致睾酮形成减少。我们建议如下：(一)改变余额 在活性氧积累和抗氧化防御系统之间导致氧化增加 应激，进而导致质膜上的信号转导级联受损，从而 衰老的间质细胞对黄体生成素的反应性降低。(Ii)因此而老化 与年轻细胞相比，细胞产生的cAMP更少，导致细胞内胆固醇转移到 线粒体因此减少了睾丸激素底物的可获得性。第一个目标是确定 氧化应激增加引起大鼠脑内cAMP和睾酮生成减少的机制 衰老的间质细胞。我们将检验这一假设，即为了应对增加的氧化应激，存在 促黄体生成素受体(LHR)与Gs蛋白偶联缺陷，导致对促黄体生成素反应的cAMP减少 刺激。第二个目标将检验假设，由于黄体生成素迟钝的能力 刺激衰老间质细胞产生cAMP，转运蛋白(TSPO)水平降低， 类固醇合成急性调节蛋白(STAR)动员的胆固醇，因此转移效率较低 胆固醇进入线粒体膜内层。我们进一步假设，减少的表达 衰老细胞中的TSPO是由于自然反义转录本(NAT)表达减少所致。第三 目的是确定棕色挪威大鼠间质细胞的年龄相关变化与 老化的人类睾丸。为了达到这个目的，我们将把我们在老鼠身上的发现应用到人类身上。为此，我们将 检测青壮年男性睾丸内液中的睾酮和ROS水平，捕获间质细胞 从睾丸活检组织中分析类固醇生成酶的表达及其相关蛋白的表达 在活性氧产生和抗氧化防御系统中，并检查蛋白质和脂质 在使用固定组织的情况下，PRO/抗氧化剂的平衡发生变化而受损。

The studies proposed in this MERIT extension application address the molecular mechanisms by which age-induced changes in the microenvironment of Leydig cells, the cells responsible for testicular androgen biosynthesis, lead to reduced testosterone formation. We propose the following: (i) Changes in the balance between reactive oxygen accumulation and the antioxidant defense system result in increased oxidative stress which, in turn, results in damage to the signal transduction cascade at the plasma membrane and thus in reduced responsiveness of aged Leydig cells to luteinizing hormone (LH). (ii) As a consequence, aged cells produce less cAMP than young cells, resulting in reduced intracellular cholesterol transport into the mitochondria and therefore reduced substrate availability for testosterone. The first aim is to determine the mechanism by which increased oxidative stress elicit reductions in cAMP and testosterone production in aged Leydig cells. We will test the hypothesis that in response to increased oxidative stress, there is defective coupling of LH receptors (LHR) to Gs proteins, resulting in reduced cAMP in response to LH stimulation. The second aim will test the hypothesis that as a consequence of the blunted ability of LH to stimulate cAMP production in aged Leydig cells, there are reduced levels of translocator protein (TSPO) and steroidogenic acute regualtory protein (STAR)-mobilized cholesterol, and thus less efficient transfer of cholesterol to the inner mitochondrial membrane. We further hypothesize that the reduced expression of TSPO in aged cells results from that reduced expression of Natural Antisense Transcripts (NATs). The third aim is to determine how the age-related changes in Brown Norway rat Leydig cells compare to those in aging human testes. With this aim, we will translate our findings in the rat to the human. To this end, we will measure testosterone and ROS levels in intratesticular fluid from young and aged men, capture Leydig cells from testicular biopsies to analyze steroidogenic enzyme expression and the expression of proteins involved in reactive oxygen production and in the antioxidant defense system, and examine proteins and lipids damaged by changes in the pro/antioxidant.balance using fixed tissue.