MECHANISMS IN THE REGULATION OF PROLACTIN SECRETION

催乳素是一种脑下垂体激素，参与许多生殖和 非生殖过程。催乳素瘤是最常见的 激素分泌型垂体瘤与催乳素(PRL)高分泌 与女性有关的主要神经内分泌相关病理 不孕不育。与大多数内分泌细胞不同，乳酸菌需要连续的 抑制，以保持其分泌活动在控制之下。大多数人 这种抑制来自下丘脑多巴胺(DA)。这种抑制作用 影响与众多的刺激行动相协调 促分泌剂在某些生理条件下引起催乳素激增 条件。反过来，两者都受到卵巢类固醇雌激素的调节。 这些调节剂对催乳素释放的综合或顺序影响是 人们对此知之甚少。此外，乳酸菌的亚群可能会表现出 对不同调节剂的反应不同。因此，最终的 关于推测催乳素的生理作用的结论 监管机构仍然难以捉摸。 调节催乳素调节作用的细胞事件的阐明 是了解它们在PRL分泌中的生理作用所必需的。 此外，乳酸菌亚群的鉴定 受这些监管机构的不同影响是固有的 理解。人们对离子机制知之甚少。 参与内分泌细胞的兴奋-分泌偶联 对Ca~(2+)的需求和再生电反应的存在 在细胞膜上。L)之间的功能耦合考察 膜电事件，2)胞内钙离子和3)胞吐 释放催乳素是了解催乳素生理的第一步 分泌物。 这份修订后的提案概述了一种多学科的实验方法。 促性腺激素释放调节机制的研究进展 乳酸菌从正常大鼠脑垂体前叶组织中分离出来。三 最先进的技术进步使这种调查方法 可能在正常的内分泌细胞：L)阳性鉴定为活的， 反向溶血法在混合细胞群中分泌催乳素的细胞 菌斑分析；2)全细胞和单通道电导记录 使用千兆海豹膜片钳技术；以及3)直接测量 荧光法测定单细胞胞浆内钙离子浓度 钙指示剂Fura-2的显微镜和动态成像。vbl.使用 这些在体外细胞上的技术，短期目标是 项目是鉴定和表征离子和生化 传递DA和雌激素对PRL释放的作用的信息。 个人行动的潜在机制的表征 调制器将建立理解集成的必要基础 催乳素生理变化过程中的神经内分泌功能 分泌物。此外，这项研究将提供一个框架，在其中 检查与以下相关的细胞和膜特性及异常 激素分泌的病理学。因此，这些研究具有直接的 对生育和生殖的调节以及在 高催乳素血症的临床处理。

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.