Non-opioid Actions of Dynorphin A in Anterior Pituitary

强啡肽 A 对垂体前叶的非阿片类作用

• 批准号: 6226161
• 负责人: HAZEL H SZETO
• 金额: $ 12.41万
• 依托单位: CALIFORNIA PACIFIC MED CTR RES INSTITUTE
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-30 至 2002-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6226161
• 关键词: NMDA receptors; adrenocorticotropic hormone; cortisol; drug tolerance; dynorphins; embryo /fetus; embryo /fetus tissue /cell culture; endorphins; hormone regulation /control mechanism; hypothalamic pituitary axis; pituitary gland; protein structure function; sheep

DESCRIPTION: (Applicant's Abstract) The high density of k-opioid receptors in the hypothalamus and the high concentration of Dyn peptides in both hypothalamus and pituitary suggest a possible involvement of Dyn in neuroendocrine regulation. Recent studies in the ovine fetus have led us to propose that Dyn is an important secretagogue of ACTH, and that Dyn may act via non-opioid as well as opioid mechanisms. Specifically, we hypothesize that Dyn releases ACTH via two different, but complementary, pathways. Dyn can act on k-opioid receptors in the hypothalamus to release CRH and AVP. In addition, it is hypothesized that Dyn is co-released with AVP and CRH from the hypothalamus, and this Dyn pool can then act on non-opioid receptors in the anterior pituitary to release ACTH and b-endorphin (bEnd). The goal of this project is to understand the regulatory control of both opioid and non-opioid pathways involved in the release of ACTH and bEnd by Dyn. Our specific aims are: 1) To understand the mechanisms behind the non-opioid actions of Dyn in the anterior pituitary. We hypothesize that Dyn and/or its metabolite(s) may act via the NMDA receptor or via a novel unidentified receptor in the anterior pituitary. To gain some insight into the structural specificity of this receptor, we plan to compare the activity of a number of Dyn-related peptides; 2) To determine if tolerance develops to both the opioid and non-opioid component of Dyn's action with repeated Dyn exposure. We hypothesize that tolerance will only develop to the hypothalamic opioid component and that NMDA plays a role in mediating this process; 3) To determine if cortisol plays a negative feedback role in down-regulating the opioid and non-opioid component of Dyn's action. We hypothesize that only the hypothalamic opioid component will be subjected to negative feedback control by cortisol. A combination of in vivo (chronically-instrumented ovine fetus preparation) and in vitro (primary cultures of ovine fetal anterior pituitary cells) techniques will be used. The proposed studies will significantly enhance our understanding of the role of Dyn in neuroendocrine function and the regulatory control of its complex mechanisms of action. Besides sharing the common theme of non-opioid actions of Dyn A, this component will share active interaction with all other components. Dr. Lee will provide the Dyn-related peptides for structure-activity studies; Dr. Hook will advise us on the relevant endogenous Dyn-related peptides to be tested for ACTH release; our data will be provided to Dr. Weinstein for molecular modeling.

产品说明：（申请人的摘要）下丘脑中k-阿片受体的高密度和下丘脑和垂体中Dyn肽的高浓度表明Dyn可能参与神经内分泌调节。 最近在羊胎儿中的研究使我们提出Dyn是ACTH的重要促分泌剂，并且Dyn可能通过非阿片类以及阿片类机制起作用。具体来说，我们假设Dyn通过两种不同但互补的途径释放ACTH。 强啡肽可作用于下丘脑K-阿片受体，释放CRH和AVP。 此外，假设Dyn与AVP和CRH从下丘脑共同释放，并且该Dyn池然后可以作用于垂体前叶中的非阿片受体以释放ACTH和b-内啡肽（弯曲）。 本项目的目标是了解Dyn释放ACTH和弯曲所涉及的阿片和非阿片途径的调节控制。我们的具体目标是：1）了解Dyn在垂体前叶的非阿片类作用背后的机制。 我们推测Dyn和/或其代谢产物可能通过NMDA受体或通过垂体前叶中的一种新的未知受体发挥作用。 为了深入了解这种受体的结构特异性，我们计划比较许多Dyn相关肽的活性; 2）为了确定在重复Dyn暴露的情况下是否对Dyn作用的阿片类和非阿片类成分产生耐受性。 我们假设耐受只会发展到下丘脑阿片成分，NMDA在介导这一过程中起作用; 3）确定皮质醇是否在下调Dyn作用的阿片和非阿片成分中起负反馈作用。 我们假设只有下丘脑阿片成分会受到皮质醇的负反馈控制。 将使用体内（长期内插绵羊胎仔制备）和体外（绵羊胎仔垂体前叶细胞原代培养物）技术的组合。 拟议的研究将显着增强我们对Dyn在神经内分泌功能中的作用及其复杂作用机制的调节控制的了解。 除了分享强啡肽A的非阿片类药物作用的共同主题外，该组分将与所有其他组分分享积极的相互作用。 Dr. Lee将提供Dyn-related peptides用于结构-活性研究; Dr. Hook将为我们提供关于ACTH释放测试的相关内源性Dyn-related peptides的建议;我们的数据将提供给Dr. Weinstein用于分子建模。