Neuroendo Signal Transduction in Reproductive Physiology

生殖生理学中的神经内信号转导

• 批准号: 6791819
• 负责人: KAREN Ann GREGERSON
• 金额: $ 12.24万
• 依托单位: SAINT LOUIS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-01-01 至 2004-10-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6791819
• 关键词: animal puberty; biological models; biological signal transduction; bioperiodicity; cell proliferation; dopamine; estrus; female; fertility; gene expression; genetically modified animals; hormone biosynthesis; hormone regulation /control mechanism; immunocytochemistry; laboratory mouse; lactation; membrane potentials; model design /development; neuroendocrine system; pituitary gland; potassium channel; pregnancy; prolactin; reproductive system pharmacology; secretion

DESCRIPTION (provided by applicant): Prolactin (PRL), an anterior pituitary hormone, has profound effects on female fertility. Hypersecretion of PRL is the major neuroendocrine-related pathology associated with female infertility. Isolated PRL deficiency, while rare, also results in reduced fertility and lactational failure in women. The underlying defects which lead to the common hypersecretion of PRL remain ill-defined, as do many of the mechanisms involved in the normal regulation of episodic PRL release. Usually, PRL secretion is under tonic inhibition by hypothalamic dopamine (DA). Periodic, physiological surges of PRL in females require a withdrawal from this dopaminergic inhibition. The fact that reduced responsiveness to DA is a hallmark of hyperprolactinemic syndromes demanded that we focus our attention on the cellular and molecular basis of DA action on the lactotrope. We have discovered and extensively characterized a DA-activated inwardly-rectifying potassium channel (KDA) in normal female lactotropes. DA regulates lactotrope membrane excitability through activation of KDA and in vitro studies have demonstrated a critical role for this KDAchannel in the regulation of PRL release by DA. Furthermore, the functional expression of KDAis dependent upon estrogen, which may explain a long-recognized modulatory action of estrogen on this system. In these regards, the KDA channel occupies a primal position in the hierarchy of events in dopaminergic regulation of PRL secretion. We have proposed to evaluate the role of this effector K channel within its physiological context - the whole animal through transgenic technology. To this end, we have designed and constructed "dominant negative" mutants, capable of inhibiting wild-type KDA function in lactotropes. We then created a transgenic mouse model ("Loss of Function") in which expression of this mutant is directed to pituitary lactotropes using the PRL promoter. A second transgenic model ("Gain of Function") has also been produced in which a constitutively active K channel, with the same biophysical properties as KDA, is over expressed in the lactotropes. Both models exhibit altered PRL secretory activity. These two models will enable us to study the physiological role of KDAand membrane excitability in the regulation of both basal and episodic release of PRL. Such studies will ultimately provide insight into the basis of secretory disorders in PRL, a hormone at the core of mammalian fertility, gestation and lactation.

描述（由申请人提供）：前垂体激素催乳素（PRL）对女性的生育能力产生深远影响。 PRL的过度分泌是与女性不育症相关的主要神经内分泌相关病理。孤立的PRL缺乏症虽然很少见，但也导致女性的生育能力和泌乳衰竭降低。导致普通过度分泌PRL的基本缺陷仍然不明显，并且许多与正常调节PRL释放相关的机制也是如此。通常，PRL分泌受到下丘脑多巴胺（DA）的强直抑制作用。雌性PRL的周期性生理激增需要从这种多巴胺能抑制中退出。对DA的反应性降低是多丙泊蛋白综合征的标志，这一事实要求我们将注意力集中在DA作用对乳糖的细胞和分子基础上。 我们已经发现并广泛地表征了正常雌性乳突中的DA激活的内向钾通道（KDA）。 DA通过激活KDA调节乳糖膜的兴奋性，并且体外研究表明，该KDachannel在DA调节PRL释放中起着至关重要的作用。此外，KDAI的功能表达取决于雌激素，这可以解释雌激素对该系统的长期认可的调节作用。在这些方面，KDA渠道在PRL分泌的多巴胺能调节中的事件层次结构中占据了原始地位。 我们建议评估该效应k渠道在其生理环境中的作用 - 通过转基因技术的整个动物。为此，我们设计并构建了“显性负”突变体，能够抑制乳型中的野生型KDA功能。然后，我们创建了一个转基因小鼠模型（“函数丧失”），其中该突变体的表达使用PRL启动子将其定向到垂体乳糖。还产生了第二个转基因模型（“功能的增益”），其中在乳糖中表达了具有与KDA相同的生物物理特性的组成型活性K通道。两种模型都表现出改变的PRL分泌活动。这两个模型将使我们能够研究KDAAND膜兴奋性在调节PRL基础和情节释放中的生理作用。此类研究最终将提供有关PRL分泌障碍基础的洞察力，PRL是哺乳动物生育能力，妊娠和泌乳的核心的激素。