MOLECULAR DYNAMICS OF GONADOTROPINS

为了了解控制脊椎动物生殖周期的调控机制，重要的是确定性腺外(垂体促性腺激素)和性腺内(类固醇激素和性腺肽)分子的层次结构，并破译它们的间歇性释放如何刺激性腺发育。促性腺激素(GTH)间歇性分泌紊乱经常导致人类不孕。GTHs脉冲性释放的病因、发育和分子方面在很大程度上尚不清楚。对几种性腺肽与性腺功能信号之间的关系的了解还很初级。该项目的长期目标是在分子水平上表征GTHs的释放与卵巢类固醇和性腺肽的节律性分泌之间的发育和动态相互作用。在整个生殖周期中，17β-雌二醇(E_2)的周期性释放似乎在调节GTH的分泌方面具有编程作用。尽管决定动物和人类循环促性腺激素水平的最重要的生理决定因素似乎是类固醇状态，但不能排除性腺肽也起关键作用的假设。这一建议旨在测试雌激素和性腺多肽(抑制素和肌动蛋白)优先调控促性腺激素mRNA亚单位表达的实验范式。将通过Norther印迹分析和核糖核酸酶保护分析来评估性类固醇(特别是E2的作用)和性腺肽对脑垂体GTH亚单位mRNA表达的调节。将产生针对GTH亚单位的抗体，以建立相应的放射免疫分析来测量GTH水平，并验证GTH的循环产生受到性腺肽和类固醇的影响的假设。除了在垂体水平上的抑制素作用外，性腺肽可能作为卵巢功能的旁分泌和自分泌调节的关键作用的假说将通过卵巢卵泡细胞培养来评估。阐明促性腺激素、性腺肽和类固醇控制间歇性生殖活动的分子和生物学机制，不仅可以为理解人类的基本生产过程提供新的见解，而且很可能为揭示人类月经失调的病因提供新的见解。

To understand the regulatory mechanisms involved in controlling the vertebrate reproductive cycle, it is important to identify the hierarchy of extragonadal (pituitary gonadotropic hormones) and intragonadal (steroid hormones and gonadal peptides) molecules and to decipher how their episodic releases stimulate gonadal development. Derangements in the episodic secretion of gonadotropins (GTHs) frequently cause infertility in humans. The etiologies, and the developmental and molecular aspects of the pulsatile GTHs release are largely unknown. The understanding of the relationship of several gonadal peptides to the signals for gonadal function is still very elementary. The long-term goal of this project is to characterize the developmental and dynamic interaction between the release of GTHs and the rhythmic secretion of ovarian steroids and gonadal peptides at the molecular level. The periodic release of 17beta-estradiol (E2) throughout the reproductive cycle appears to have a programming role in the modulation of GTHs secretion. Although the most important physiological determinant of circulating gonadotropin levels in animals and humans appears to be the steroid status, the hypothesis that gonadal peptides also play a critical role cannot be ruled out. This proposal is designed to test the experimental paradigms that both estradiol and gonadal peptides (inhibin and actin) preferentially modulate gonadotropins mRNA subunits expression. Regulation of GTH subunit mRNA expressions by sex-steroids (in particular the action of E2) and gonadal peptides on the pituitary gland will be assessed using Norther blot analysis and ribonuclease protection assay. Antibodies against the GTH subunits will be generated in order to develop a homologous radioimmunoassay to measure GTH levels and to test the hypothesis that the cyclic production of GTHs is under both gonadal peptides and steroids influence. In addition to the inhibin effects at the pituitary level, the hypothesis that gonadal peptides may play a crucial role as paracrine and autocrine regulator of ovarian functions will be assessed using ovarian follicle cell cultures. The elucidation of the molecular and biological mechanisms by which gonadotropins, gonadal peptides and steroids control episodic reproductive activities may provide new insights for understanding not only the basic productive process, but also very possibly unravel the etiologies of menstrual dysfunction in humans.