MECHANISM OF ACTION OF GONADOTROPINS IN THE TESTIS

这个项目的长期目标是描述这些机制的特征 这决定了间质细胞产生睾酮的能力。我们 我通过研究活动的关系来探讨这个问题 两种类固醇生物合成酶对最大睾酮产量的影响 功能不同的间质细胞与正常和 用促性腺激素治疗的大鼠。本研究的具体目的是 旨在评估类固醇合成途径中的其他部位，这些部位可能 在确定睾丸间质细胞产生睾酮的能力方面起决定性作用 以及阐明促黄体生成素(黄体生成素) 和cAMP增加或减少最大睾丸素的产生 这取决于他们的管理模式。具体来说，我们将 测定：1)胆固醇侧链的活性是否断裂 酶(P-450scc)在间质细胞和间质细胞两个群体中不同。 促黄体生成素长期体内治疗是否增加血管活性 使用间质匀浆或浓缩线粒体部分的P-450scc 甲硝胺梯度法将细胞分为两个群体 2)催乳素在调节乳汁中的作用。 5纯化的大鼠间质细胞性期α-还原酶活性 成熟；3)cAMP导致类固醇生成的机制 使用新开发的小鼠间质细胞培养系统进行脱敏。 这第三个具体目标将考察cAMP引起 微粒体和线粒体P-450酶活性降低， 微粒体和线粒体P-450降低之间的关系 最大睾酮的活性、底物耗竭和降低 制作。将使用[~3H]标记的类固醇来研究酶的活性 提取和测定[~3H]标记类固醇产物的底物和方法 用薄层层析法纯化甾体化合物。 建议采用体内和体外相结合的研究 研究间质细胞功能调节的方法将有助于 更好地理解决定最大睾丸素的过程 不同生命阶段和不同病理状态下的生产 条件。

The long term objective of this project is to characterize the mechanisms that determine the capcity of Leydig cells to produce testosterone. We have approached this problem by studying the relationship of activities of steroid biosynthetic enzymes to maximal testosterone production in two functionally distinct populations of Leydig cells from normal and gonadotropin-treated rats. The specific aims of the present study are designed to evaluate additional sites in the steroidogenic pathway that may be decisive in determining Leydig cell capacity for testosterone production as well as to elucidate the mechanisms by which luteinizing hormone (LH) and cAMP either increase or decrease maximal testosterone production depending on the mode of their administration. Specifically we will determine: 1) whether the activity of the cholesterol side chain cleavage enzyme (P-450scc) differs in the two populations of Leydig cells and whether chronic in vivo treatment with LH increases the activity of P-450scc' using homogenates or enriched mitochondrial fractions of Leydig cells separated into two populations by Metrizamide gradient centrifugation; 2) the role of prolactin in the regulation of 5Alpha-reductase activity in purified rat Leydig cells during sexual maturation; and 3) the mechanism by which cAMP brings about steroidogenic desensitization using a newly developed mouse Leydig cell culture system. This third specific aim will examine the mechanisms by which cAMP causes decreases in microsomal and mitochondrial P-450 enzyme activities and the relationship among decreases in microsomal and mitochondrial P-450 activities, substrate depletion and reductions in maximal testosterone production. Enzyme activities will be studied using [3H]-labeled steroid substrates and measuring [3H]-labeled steroid products after extraction and purification of steroids by thin-layer chromatography. The proposed studies using the combination of in vivo and in vitro approaches to study regulation of Leydig cell function will contribute to a better understanding of the processes that determine maximal testosterone production at different stages of life and under different pathological conditions.