MECHANISMS IN THE REGULATION OF PROLACTIN SECRETION

催乳素分泌的调节机制

基本信息

批准号：
2391412
负责人：
KAREN Ann GREGERSON
金额：
$ 20.29万
依托单位：
UNIVERSITY OF MARYLAND BALTIMORE
依托单位国家：
美国
项目类别：
财政年份：
1988
资助国家：
美国
起止时间：
1988-08-01 至 1999-03-31
项目状态：
已结题

项目摘要

Prolactin is a pituitary hormone involved in numerous reproductive and non-reproductive processes. Prolactinomas are the most common of the hormone-secreting pituitary tumors and hypersecretion of prolactin (pRL) is the major neuroendocrine-related pathology associated with female infertility. Unlike most endocrine cells, lactotropes require continuous inhibition to keep their secretory activity under control. The majority of this inhibition comes from hypothalamic dopamine (DA). This inhibitory influence coordinates with the stimulatory actions of numerous secretagogues to elicit surges of PRL under certain physiological conditions. Both, in turn, are modulated by the ovarian steroid, estrogen. The combined or sequential effects of these regulators on PRL release are poorly understood. Moreover, subpopulations of lactotropes may exhibit differences in responsiveness to the various modulators. Thus, definitive conclusions regarding the physiological roles of putative prolactin regulators remain elusive. Elucidation of the cellular events mediating the actions of PRL regulators is required for understanding their physiological role in PRL secretion. In addition, identification of subpopulations of lactotropes differentially affected by these regulators is inherent to this understanding. Relatively little is known about the ionic mechanisms involved in excitation-secretion coupling in endocrine cells beyond a requirement for Ca2+ and the presence of regenerative electrical responses in the cell membrane. Investigation of the functional coupling between l) membrane electrical events, 2) cytosolic Ca2+ and 3) the exocytotic release of PRL is the first step to understanding the physiology of PRL secretion. This revised proposal outlines a multidisciplinary experimental approach to the study of mechanisms in the regulation of PRL release from lactotropes dissociated from normal rat anterior pituitary tissue. Three state-of-the-art technological advances make this investigative approach possible in normal endocrine cells: l) positive identification of viable, PRL-secreting cells in mixed cell populations using the reverse hemolytic plaque assay; 2) recording of whole cell and single channel conductances using giga-seal patch clamp techniques; and 3) direct measurement of cytoplasmic Ca2+ concentration in single cells using fluorescent microscopy and dynamic imaging of the calcium indicator fura-2. Using these techniques on cells in vitro, the short-term objectives of this project are to identify and characterize the ionic and biochemical messages transducing the actions of DA and estrogen on PRL release. Characterization of the mechanisms underlying the action of individual modulators will establish the necessary basis for understanding integrated neuroendocrine function during physiological changes in prolactin secretion. In addition, this research will provide a framework in which to examine cellular and membrane properties and abnormalities associated with pathologies of hormone secretion. As such, these studies have a direct bearing on the regulation of fertility and reproduction and in the clinical management of hyperprolactinemia.

催乳素是参与许多生殖和非生产过程。催乳素瘤是最常见的分泌激素的垂体肿瘤和催乳素的过度分泌（PRL）是与女性相关的主要神经内分泌相关病理不育。与大多数内分泌细胞不同，乳酸需要连续抑制以控制其分泌活动。大多数这种抑制作用来自下丘脑多巴胺（DA）。这种抑制作用影响众多刺激作用的坐标在某些生理学下引起PRL的促销状况。反过来，两者均由卵巢类固醇，雌激素调节。这些调节剂对PRL释放的合并或顺序效应是理解不佳。此外，乳糖的亚群可能表现出来对各种调节器的响应能力差异。因此，确定性关于假定催乳素的生理作用的结论监管机构仍然难以捉摸。阐明介导PRL调节剂作用的细胞事件需要了解其在PRL分泌中的生理作用所必需的。此外，鉴定乳糖的亚群受这些调节器的差异影响是固有的理解。关于离子机制的知之甚少参与内分泌细胞中的激发 - 分泌耦合以外 CA2+的需求和再生电响应的存在在细胞膜中。研究L之间的功能耦合）膜电气事件，2）胞质CA2+和3）胞吐 PRL的释放是理解PRL生理学的第一步分泌。该修订的建议概述了一种多学科实验方法在调节PRL释放中的机制乳糖与正常大鼠前垂体组织分离。三最先进的技术进步使这种调查方法在正常内分泌细胞中可能可能使用反向溶血的混合细胞种群中的PRL分泌细胞分泌细胞斑块测定； 2）记录全电池和单个通道电导使用Giga-seal贴片夹技术； 3）直接测量使用荧光的单细胞中的细胞质Ca2+浓度钙指标Fura-2的显微镜和动态成像。使用这些在体外细胞上的技术，这是其中的短期目标项目旨在识别和表征离子和生化消息传递了DA和雌激素对PRL释放的作用。表征个体作用的机制调节器将建立必要的依据，以理解综合的催乳素的生理变化期间神经内分泌功能分泌。此外，这项研究将提供一个框架检查与相关的细胞和膜特性以及异常激素分泌的病理。因此，这些研究直接与生育和繁殖的调节以及高品位血症血症的临床管理。