A THECAL ROLE IN OVULATION

排卵中的主要作用

• 批准号: 2453974
• 负责人: KATHERINE F ROBY
• 金额: $ 7.5万
• 依托单位: UNIVERSITY OF KANSAS MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-01-15 至 1999-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2453974
• 关键词: chorionic gonadotropin; collagenase; dioxins; enzyme activity; female; gene expression; graafian follicles; hormone receptor; hormone regulation /control mechanism; hypophysectomy; immature animal; immunocytochemistry; in situ hybridization; laboratory rat; luteinizing hormone; ovulation; plasmin; plasminogen activator; plasminogen activator inhibitors; stromelysin

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.

排卵被描述为一种病理生理事件，其中， 控制溶解和破裂，然后修复其他 健康的组织发生。 卵泡破裂是由于 协调几种不同的细胞类型和功能。 的 每个细胞区室的特定作用参与了成功的 排卵仍在调查中。这个项目的长期目标 研究的目的是评估和了解卵泡膜在 排卵事件。 本提案中描述的实验使 一种新的排卵阻断模型的用途， 研究卵泡膜的作用。 未成熟垂体切除大鼠 用单剂量TCDD（2，3，7，8-四氯二苯并对二恶英）处理 其次是促性腺激素（PMSG和hCG）的标准方案， 排卵 用TCDD处理过的大鼠的卵巢 含有卵子的未破裂的卵泡。 这里描述的初步研究 与先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， 专门研究卵泡膜在排卵中的作用。 的 排卵过程是由黄体生成素（LH）释放启动的 从垂体中取出 作用于卵巢水平的LH增加 细胞内的cAMP，从而启动细胞内事件的级联。 一组由LH调节的基因， 促排卵的主要因素是纤溶酶原激活物（PA）和纤溶酶原激活物 抑制因子（派）基因。 作为对LH的反应，派降低，PA 增大 初步研究表明，当TCDD存在时， 不会发生排卵。 要研究的假设是， TCDD通过抑制纤溶酶原激活物系统阻断排卵， 直接在基因水平上和/或间接地影响卵巢 通过改变LH的作用。 TCDD可以直接在 的PA/派基因，和/或间接地通过TCDD诱导的抑制PA/PAI基因， LH受体介导的事件。 初步研究表明LH受体 TCDD处理后的结合没有改变，因此TCDD可能在 LH受体结合后点。 第一个目标是在这个 该提案将解决卵巢PA和派基因表达和活性 在体内用TCDD处理后。 对于这些研究不成熟 切除垂体的大鼠将先用TCDD治疗，然后用PMSG治疗， hCG。 将在hCG后的不同时间点采集卵巢 给药后，将排卵前卵泡从 子房，分为膜层和颗粒层。 因此，PA/派表达 和活性将分别在膜和颗粒中进行评估 隔间 TCDD可能会通过改变卵巢上皮细胞的能力来阻止排卵。 卵巢细胞对LH有反应。 初步研究显示LH受体 结合不受TCDD影响（TCDD与对照），然而，在体外 数据表明TCDD抑制LH刺激的cAMP积累。的 这些研究的第二个目的是评估TCDD对卵巢癌的影响。 LH受体信号传导事件。 使用类似的体内模型系统， 未成熟的垂体切除大鼠将用TCDD处理， PMSG和hCG。 排卵前hCG给药后4小时 将卵泡切开并分成卵泡膜和颗粒。 HCG 刺激cAMP、腺苷酸环化酶、磷酸二酯酶和蛋白激酶 将测定并比较对照组和TCDD组的C活性 治疗 这种通过用以下药物治疗来阻断排卵的新模型 TCDD提供了一种独特的工具来研究卵泡膜在 排卵 本提案中概述的研究开始评估 TCDD阻断排卵的机制。