The Role of Leptin in Luteal Angiogenesis (pilot)

黄体（CL）是卵巢结构，产生类固醇激素孕酮，这是必要的， 哺乳动物保持怀孕的能力。黄体缺陷导致女性不孕症 据信约占复发性流产的65%。这些黄体缺陷包括异常 黄体发育和孕酮产生减少，这部分归因于异常的血管生成，即， 血管形成在卵巢中，血管生成是一个周期性的，反复发生的过程，发生在排卵后 由脑垂体前叶分泌的促黄体生成激素（LH）激增引发的成熟卵泡。 排卵时，内膜中的毛细血管能够穿透无血管的颗粒层，这是由于 基底膜的解离，并形成窦状毛细血管网络。有很多已知的因素 调节黄体血管生成，包括血管内皮生长因子（VEGF），成纤维细胞生长因子2（FGF-2）， 血管生成素1（Ang-1）和瘦素。据报道，所有这些因子都是在卵巢中产生的;此外，VEGF， 据报道，Ang-1和FGF-2在黄体组织中产生，对应于高血管生成活性的时期。 促黄体激素暴露后黄体VEGF、FGF-2和Ang-1基因表达上调 LH，它也刺激卵巢产生瘦素，一种有效的饱腹感激素。瘦素是一种重要的代谢调节因子， 由脂肪细胞产生的激素，已知具有生殖和有效的血管生成功能特性。 此外，已知瘦素影响非卵巢组织中VEGF、FGF-2和Ang-1的功能。此外，委员会认为， 瘦素受体（OB-Rb）的全功能形式已在黄体组织中被鉴定， 激活AP-1 DNA元件的转导级联，AP-1 DNA元件是已知启动VEGF，FGF-2， Ang-1因此，LH可能通过影响VEGF、FGF-1基因表达启动血管化过程。 2、Ang-1和瘦素。瘦素可能进一步介导LH的作用，通过其对血管生成过程的影响， 调节或与其他黄体血管生成因子的相互作用。因此，瘦素在血管生成中的作用 黄体组织的过程还没有很好的定义，但是，瘦素影响VEGF，FGF-2和Ang-1的能力在各种不同的黄体组织中， 非卵巢组织，黄体组织中OB-Rb的存在，以及OB-Rb激活信号转导的能力 已知调节VEGF、FGF-2和Ang-1转录激活的级联反应表明，瘦素可能在 在黄体血管生成中的作用。因此，本文提出的研究的具体目的是：1）组织学鉴定 VEGF、Ang-1、FGF-2和OB-Rb在黄体组织中的时空定位， 黄体期，2）定量测定卵巢癌组织中VEGF、Ang-1、FGF-2和OB-Rb mRNA和蛋白质之间的时间关系 黄体期不同阶段的CL; 3）测定瘦素对VEGF、Ang-1和FGF-2的影响 在发情周期的早期、中期和晚期黄体组织中的基因和蛋白质表达，和4） 确定瘦素在体内黄体血管生成中的作用。

The corpus luteum (CL) is an ovarian structure that produces the steroid hormone progesterone, which is imperative to the maintenance of pregnancy in mammalian species. Corpora luteal defects contribute to infertility issues in women and are believed to account for approximately 65% of recurrent miscarriages. These luteal defects include abnormal luteal development and decreased progesterone production, which are attributed, in part, to abnormal angiogenesis, i.e., vascular formation. In the ovary, angiogenesis is a cyclical, recurring process that takes place following the ovulation of a mature follicle initiated by a surge of secreted luteinizing hormone (LH) from the anterior pituitary of the brain. Upon ovulation, the capillaries in the theca interna are able to penetrate the avascular, granulosal layer, as a result of the dissociation of the basement membrane, and form a network of sinusoidal capillaries. There are many factors known to regulate luteal angiogenesis, including vascular endothelial growth factor (VEGF), fibroblast growth factor 2 (FGF-2), angiopoietin 1 (Ang-1), and leptin. All of these factors are reported to be produced in the ovary; moreover, VEGF, Ang-1, and FGF-2 are reported to be produced in luteal tissue corresponding to periods of high angiogenic activity. Upregulation of luteal VEGF, FGF-2, and Ang-1 gene expression occurs following exposure to the luteotropic hormone LH, which also stimulates ovarian production of leptin, a potent satiety hormone. Leptin is an important metabolic hormone produced by adipocytes that is known to have both reproductive and potent angiogenic functional properties. Furthermore, leptin is known to influence the function of VEGF, FGF-2, and Ang-1 in non-ovarian tissues. Moreover, the fully functional form of the leptin receptor (OB-Rb) has been identified in luteal tissue and stimulates a signal transduction cascade that activates the AP-1 DNA element, a site known to initiate gene transcription of VEGF, FGF-2, and Ang-1. Therefore, LH may initiate the vascularization process by influencing the gene expression of VEGF, FGF- 2, Ang-1, and leptin. Leptin may then further mediate the effects of LH, influencing the angiogenic process through its regulation or interaction with the other luteal angiogenic factors. Hence, the role of leptin in the angiogenic processes of luteal tissue is not well-defined, but, leptin's ability to influence VEGF, FGF-2, and Ang-1 in various non-ovarian tissues, the presence of OB-Rb in luteal tissue, and OB-Rb's ability to activate a signal transduction cascade known to regulate transcriptional activation of VEGF, FGF-2, and Ang-1 suggests that leptin may play a role in luteal angiogenesis. Therefore, the specific aims of the study proposed herein are to 1) histologically identify spatial and temporal localization of VEGF, Ang-1, FGF-2, and OB-Rb in luteal tissue during the different stages of the luteal phase, 2) quantitate the temporal relationship among VEGF, Ang-1, FGF-2, and OB-Rb mRNA and protein in the CL during different stages of the luteal phase, 3) determine leptin's ability to influence VEGF, Ang-1, and FGF-2 gene and protein expression in luteal tissue during the early-, mid-, and late luteal phase of the estrous cycle, and 4) determine the role of leptin on luteal angiogenesis in vivo.