KNOCK-OUT OF K+ CHANNEL IN PITUITARY--PROLACTIN CONTROL AND FEMALE FERTILITY

垂体K通道的敲除--催乳素控制与女性生育力

• 批准号: 6318365
• 负责人: KAREN Ann GREGERSON
• 金额: $ 13.96万
• 依托单位: UNIVERSITY OF MARYLAND BALTIMORE
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-04-01 至 2001-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6318365
• 关键词: Xenopus oocyte; cooperative study; dopamine; estrogens; female; female reproductive system; fertility; gene mutation; gene targeting; genetically modified animals; hormone regulation /control mechanism; immunocytochemistry; laboratory mouse; luteinizing hormone; molecular cloning; pituitary gland; potassium channel; prolactin; reproduction; secretion; voltage /patch clamp

Prolactin (PRL), an anterior pituitary hormone, has profound effects on female fertility. In fact, hypersecretion of PRL is the major neuroendocrine-related pathology associated with female infertility. Unfortunately, the underlying defects which lead to the hypersecretion of PRL remain ill-defined. To provide a rational framework for understanding these defects and treating associated pathologies, it is essential to elucidate the cellular and molecular mechanisms of PRL secretion regulation. Normally, PRL secretion is under tonic inhibition by hypothalamic dopamine (DA). Periodic, physiological surges of PRL in females require a withdrawal from this dopaminergic inhibition. Since reduced responsiveness to DA is a hallmark of hyperprolactinemic syndromes, our attention has focused 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 (K/DA) in normal lactotropes. K/DA activation by DA leads to hyperpolarization of the lactotrope membrane and cessation of calcium-dependent action potentials, the driving force for tonic PRL secretion. In vitro studies have demonstrated a critical role for this D/DA channel in the regulation of PRL release by DA. Furthermore, the functional expression of D/DA is dependent upon estrogen, which may explain a long-recognized modulatory action of estrogen on this system. In these regards, the D/DA channel lies at the top of a hierarchy of events in dopaminergic regulation of PRL secretion. As an initial step in elucidating the molecular basis for the physiological role of K/DA in lactotropes, we have cloned three different K channel gene products from female anterior pituitary tissue. Based on functional similarities between the native channel and recombinant channels expressed in Xenopus oocytes, two of the gene products are excellent candidate subunits encoding a heteromultimeric K/DA. As a logical extension of these studies, we propose to evaluate the role of this effector K channel within its physiological context-the whole animal- through transgenic technology. To this end, we will design and construct "dominant-negative" mutants, capable of inhibiting wild-type K/DA function in lactotropes. We will then create a transgenic mouse model in which expression of this mutant is directed to pituitary lactotropes using the PRL promoter. These studies represent a timely and important extension of the P.I.'s work and will ultimately provide insight into the basis of disorders in PRL secretion and their impact on female fertility.

催乳素（PRL）是一种脑垂体前叶激素，对人体有深远的影响