Endothelin-2 in Ovarian Follicle Rupture

描述(申请人提供)：本研究的目的是阐明内皮素-2(EDN-2)在卵泡破裂中的作用机制。排卵程序是由黄体生成素的激增激活的，黄体生成素启动卵巢的分子、生化和物理方面的戏剧性变化，最终导致卵泡破裂。然而，卵泡破裂过程中涉及的因素和调控机制尚不清楚。利用基因表达谱方法，我们已经确定了EDN-2，一种强大的平滑肌收缩因子，它在排卵前立即在排卵周卵泡的颗粒细胞中特异地瞬时表达。我们发现EDN-2诱导卵巢组织快速而持续的收缩，而内皮素受体拮抗剂替佐生则释放这种收缩。这些新的发现使我们假设EDN-2直接收缩排卵周卵泡，导致卵泡破裂。免疫组织化学分析证实，每个卵泡的外膜有一层组织良好的平滑肌层，在整个卵巢水平上形成了一个海绵状的平滑肌网络，支持了这一假说。此外，我们发现排卵前卵巢内注射替佐生能完全阻止卵泡破裂。本研究旨在阐明EDN-2在卵泡破裂中的作用机制。我们将确定EDN-2作用的靶组织，介导EDN-2作用的内皮素受体亚型(S)，以及卵巢中EDN-2的浓度。我们还将确定内皮素-2诱导的卵泡收缩的机制与其他卵巢产生的血管收缩分子(VIP、PACAPs和前列腺素)的关系。此外，还将探讨与EDN-2相关的黄体酮、雌激素和前列腺素与卵泡破裂的功能联系。这一建议的主要优势在于确定EDN-2和卵巢平滑肌网是卵泡破裂的关键组成部分。提出的实验的新颖性是跨学科的方法(全基因组基因表达谱、卵巢内注射和等长张力测量)。为了进一步了解卵泡破裂的机制，所提出的研究具有特别重要的意义。拟议的实验将为确定治疗女性不孕不育的主要原因之一的烦躁症状的治疗靶点提供临床指导。

DESCRIPTION (provided by applicant): The goal of the proposed studies is to elucidate the mechanism of endothelin-2 (EDN-2) action in follicle rupture. The program of ovulation is activated by a surge of luteinizing hormone, which initiates dramatic changes in molecular, biochemical, and physical aspects of the ovary, eventually leading to rupture of follicles. However, the factors involved in and the mechanism governing the process of follicle rupture are yet to be unveiled. Using a gene expression profiling approach, we have identified EDN-2, a potent smooth muscle constrictor, which is exclusively and transiently expressed in the granulosa cells of periovulatory follicles immediately prior to ovulation. We found that EDN-2 induces rapid and sustained contraction in the ovarian tissue, while tezosentan, an endothelin receptor antagonist, released the contraction. These novel findings led us to hypothesize that EDN-2 directly constricts periovulatory follicles leading to the rupture of the follicle. Supporting the hypothesis, immunohistochemical analysis identified a well-organized smooth muscle layer in the theca externa of each follicle, which forms a sponge-like smooth muscle network at the whole ovarian level. Furthermore, we found that intraovarian injection of tezosentan prior to ovulation completely blocked follicle rupture. In this study, we will elucidate the mechanism of EDN-2 action in follicle rupture. We will determine the target tissues of EDN-2 action, the endothelin receptor subtype(s) that mediates EDN-2 action, and the ovarian concentration of EDN-2. We will also determine the mechanism of endothelin-2 induced follicular constriction in relation to other ovary-produced vasoconstrictive molecules (VIPs, PACAPs, and prostaglandins). In addition, the functional link of progesterone, estrogen, and prostaglandin to the follicle rupture in relation to EDN-2 will be explored. The major strength of this proposal is in the identification of EDN-2 and the ovarian smooth muscle network as the key components of follicle rupture. The novelty of the proposed experiments is the interdisciplinary approaches (genome-wide gene expression profiling, intraovarian injection, and isometric tension measurement). The proposed studies are exceptionally important in order to further our understanding of the mechanism of follicle rupture. The proposed experiments will provide clinical direction in identifying the therapeutic target for the cure of annovulatory symptoms, one of the leading causes of female infertility.