A THECAL ROLE IN OVULATION

排卵被描述为一种病理生理事件，在这种情况下 受控溶解和破裂，然后修复其他 健康的组织就会出现。卵泡破裂是由于 协调几种不同的细胞类型和功能。这个 每个细胞隔间参与的特定角色 排卵情况仍在调查中。这样做的长期目标是 研究的目的是评估和了解卵泡膜在 排卵事件。这份提案中描述的实验使 利用一种新的阻断排卵的模型来特异性地 调查膜蛋白的作用。幼龄大鼠去垂体腺 单剂TCDD(2，3，7，8-四氯二苯并-对二恶英) 紧随其后的是促性腺激素(PMSG和hCG)的标准方案 排卵。经TCDD治疗的大鼠卵巢较大 含有卵子的未破裂的卵泡。这里描述的初步研究 与之前公布的数据一起表明，TCDD直接作用于 卵泡膜的水平。该模型系统提供了一个独特的工具来 具体研究卵泡膜在排卵中的作用。这个 排卵过程是由黄体生成素(LH)释放启动的 从脑下垂体处。促黄体生成素，作用于卵巢水平增加 细胞内cAMP，从而启动一系列细胞内事件。 一组受黄体生成素调控的基因，是卵泡发育过程中所必需的 排卵是纤溶酶原激活剂(PA)和纤溶酶原激活剂 抑制物(PAI)基因。作为对促黄体生成激素的反应，PAI降低，PA 增加。初步研究表明，当存在TCDD时， 不会发生排卵。要调查的假设是 TCDD通过抑制纤溶酶原激活系统阻止排卵 卵巢要么直接在基因水平上，要么间接地 通过改变黄体生成素的作用。TCDD可以直接在一级发挥作用 PA/PAI基因，和/或通过TCDD诱导抑制 黄体生成素受体介导的事件。初步研究表明促黄体生成素受体 TCDD处理后的结合没有改变，因此TCDD可能作用于 黄体生成素受体结合后积分。本文概述的第一个目标是 提案将涉及卵巢PA和PAI基因的表达和活性 用TCDD进行体内治疗后。因为这些研究还不成熟 去垂体大鼠先用TCDD治疗，然后用PMSG和 HCG。HCG后不同时间点采集卵巢 给药后，排卵前卵泡将从 卵巢，分成膜和颗粒。因此，PA/PAI的表达 膜和颗粒的活性将分别进行评估。 车厢。TCDD可能通过改变排卵能力而阻止排卵。 卵巢细胞对黄体生成素有反应。初步研究表明黄体生成素受体 然而，在体外，TCDD不影响结合(TCDD与对照) 数据表明，TCDD抑制卵泡刺激素刺激的cAMP积聚。这个 这些研究的第二个目的是评估TCDD对卵巢的影响 黄体生成素受体信号转导事件。使用类似的活体模型系统， 未成熟的垂体切除大鼠将用TCDD治疗，然后 PMSG和hCG。人绒毛膜促性腺激素促排卵后4小时 卵泡将被解剖并分离成膜和颗粒。人绒毛膜促性腺激素 刺激型cAMP、腺苷环化酶、磷酸二酯酶和蛋白激酶 C活性将在对照组和TCDD之间进行测定和比较 治疗。这是一种新的阻断排卵的模型 TCDD提供了一种独特的工具来研究卵泡膜蛋白在 排卵。这项提案中概述的研究开始评估 TCDD阻止排卵的机制。

Ovulation has been described as a pathophysiological event in which the controlled dissolution and rupture followed by repair of otherwise healthy tissue occurs. Follicular rupture occurs as a result of coordination of several different cell types and functions. The specific roles of each cellular compartment involved in successful ovulation is still under investigation. The long-range goals of this research are to assess and understand the role of the theca in the events of ovulation. The experiments described in this proposal make use of a novel model of blockade of ovulation to specifically investigate the role of the theca. Immature hypophysectomized rats treated with a single dose of TCDD (2,3,7,8-tetrachlordibenzo-p-dioxin) followed by standard regimens of gonadotropins (PMSG and hCG) fail to ovulate. Ovaries examined from rats treated with TCDD have large unruptured follicles containing ova. Preliminary studies described here together with previously published data indicate TCDD acts directly at the level of the theca. This model system provides a unique tool to specifically investigate the role of the theca in ovulation. The process of ovulation is initiated by luteinizing hormone (LH) released from the pituitary. LH, acting at the level of the ovary increases intracellular cAMP and thus initiates a cascade of intracellular events. One set of genes regulated by LH and requisite for the process of ovulation are the plasminogen activator (PA) and plasminogen activator inhibitor (PAI) genes. In response to LH, PAI is decreased and PA increases. Preliminary studies indicate that when TCDD is present, ovulation does not occur. The hypothesis to be investigated is that TCDD blocks ovulation by inhibiting the plasminogen activator system in the ovary either directly at the level of the gene, and/or indirectly by altering the action of LH. TCDD may function directly at the level of the PA/PAI genes, and/or indirectly via a TCDD induced inhibition of LH-receptor mediated events. Preliminary studies indicate LH receptor binding following TCDD treatment is not altered, thus TCDD might act at points after LH receptor binding. The first Aim outlined in this proposal will address ovarian PA and PAI gene expression and activity following in vivo treatment with TCDD. For these studies immature hypophysectomized rats will be treated with TCDD followed by PMSG and hCG. Ovaries will be collected at various time points after hCG administration, preovulatory follicles will be dissected from the ovaries and separated into theca and granulosa. Thus, PA/PAI expression and activity will be assessed separately in the thecal and granulosal compartments. TCDD might block ovulation by altering the ability of the ovarian cells to respond to LH. Preliminary studies show LH receptor binding to be unaffected by TCDD (TCDD vs. control), however, in vitro data indicate TCDD inhibits thecal LH-stimulated cAMP accumulation. The second Aim of these studies will assess the effect of TCDD on ovarian LH receptor signaling events. Using a similar in vivo model system, immature hypophysectomized rats will be treated with TCDD followed by PMSG and hCG. Four hours after hCG administration preovulatory follicles will be dissected and separated into theca and granulosa. hCG stimulated cAMP, adenylyl cyclase, phosphodiesterase, and protein kinase C activities will be determined and compared between control and TCDD treatment. This novel model for blockade of ovulation by treatment with TCDD provides a unique tool to investigate the role of the theca in ovulation. The studies outlined in this proposal begin to assess the mechanism whereby TCDD blocks ovulation.