Mu Opioid Receptor Regulation in Neonatal Brainstem

新生儿脑干中的 Mu 阿片受体调节

• 批准号: 6730582
• 负责人: GEORGE D OLSEN
• 金额: $ 26.43万
• 依托单位: OREGON HEALTH & SCIENCE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-12-15 至 2007-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6730582
• 关键词: CHO cells; G protein; autoradiography; brain stem; disease /disorder model; drug abuse; drug withdrawal; embryo /fetus toxicology; guanosine triphosphate; guinea pigs; heroin; hyperpnea; immunocytochemistry; lung development; methadone; nucleic acid purification; opioid receptor; placental transfer; polymerase chain reaction; protein structure function; receptor binding; receptor coupling; receptor expression; respiratory disorder; transfection; transfection /expression vector

DESCRIPTION (provided by applicant): The long-term goal of the proposed research is to understand mechanisms by which chronic in utero morphine and methadone exposure affect regulation and function of mu opioid receptors (MOR) in respiratory control areas of newborn brainstem. Respiratory depression is induced by endogenous opioid peptides and exogenous opioids that activate MOR. A critical brainstem site for these effects is the nucleus tractus solitarius (NTS), which integrates sensory signals and drives respiratory muscles. Profound disturbance of neonatal breathing is a well-documented consequence of maternal opioid abuse. These neonates exhibit withdrawal hyperventilation and an increased incidence of sudden infant death syndrome (SIDS). The proposed studies are essential for understanding normal respiratory development, drug-induced changes, and effective treatment of pregnant heroin addicts and methadone maintained patients. The exact role of NTS MOR in neonatal congenital narcotic dependence and these respiratory disturbances is unknown. For anatomical, physiological, and pharmacological reasons, the guinea pig is a superb model for study of maternal opioid abuse. Guinea pig kappa opioid receptor has been cloned, but only partial sequences of MOR and delta opioid receptors have been available. However, our laboratory has recently determined the complete guinea pig MOR cDNA sequence. Availability of this sequence will enable us to define for the first time guinea pig MOR pharmacology, and systematically compare it to human and mouse MOR. Research is guided by four hypotheses: 1) guinea pig MOR is functionally similar to human MOR with respect to mu agonist efficacy, binding kinetics, and activation of G-protein, but different from murine MOR; 2) methadone induces respiratory depression and is equipotent to, but of longer duration than morphine in the neonatal guinea pig; 3) chronic in utero morphine and methadone exposure results in increased functional MOR on the cell surface, but decreases the coupling efficiency of MOR with G-proteins in the NTS; 4) chronic in utero morphine and methadone exposure up-regulates MOR mRNA in the NTS. Hypotheses are explored through four specific aims: 1) to compare mu agonist selectivity and potency, and development of cellular tolerance for guinea pig, human and murine MOR each expressed in stably transfected CHO cells; 2) to prove that the respiratory effects of methadone are similar to morphine in the neonatal guinea pig; 3) to study the effects of morphine and methadone on guinea pig MOR in NTS of brainstem sections from guinea pig neonates exposed in utero; and 4) to quantitate MOR mRNA in NTS from guinea pig neonates exposed to morphine and methadone in utero. These studies will provide developmental information on guinea pig NTS MOR following chronic in utero opioid exposure.

描述（由申请人提供）：拟议的研究的长期目标是了解新生儿脑干呼吸控制区域中MU阿片受体（MOR）的慢性吗啡和美沙酮暴露在内的机制。呼吸道抑郁是由激活MOR的内源性阿片类肽和外源性阿片类药物诱导的。这些作用的关键脑干部位是核菌solitarius（NTS），它整合了感觉信号并驱动呼吸道肌肉。新生儿呼吸的深刻干扰是母亲阿片类药物滥用的备受证明的结果。这些新生儿表现出戒断过度换气和猝死综合征（SIDS）的发病率增加。拟议的研究对于理解正常呼吸道发育，药物诱导的变化以及对怀孕海洛因成瘾者和美沙酮维持患者的有效治疗至关重要。 NTS MOR在新生儿先天性麻醉依赖性和这些呼吸障碍中的确切作用尚不清楚。出于解剖学，生理和药理原因，豚鼠是研究母体阿片类药物滥用的绝佳模型。豚鼠kappa阿片受体已被克隆，但只有MOR和Delta阿片受体的部分序列。但是，我们的实验室最近确定了完整的豚鼠MOR cDNA序列。该序列的可用性将使我们能够首次定义豚鼠MOR药理学，并系统地将其与人和小鼠MOR进行比较。研究以四个假设为指导：1）在MU激动剂功效，结合动力学和G蛋白的激活方面，豚鼠MOR在功能上与人MOR相似，但与Murine Mor不同。 2）美沙酮诱导呼吸道抑郁症，是有计划的，但持续时间比新生儿猪中的吗啡更长。 3）子宫内吗啡和美沙酮暴露的慢性导致细胞表面的功能性MOR提高，但降低了NTS中MOR与G蛋白的偶联效率。 4）子宫内吗啡和美沙酮暴露的慢性上调NTS中的MOR mRNA。假设是通过四个特定目的探索的：1）比较Mu激动剂的选择性和效力，以及对豚鼠，人和鼠类MOR的细胞耐受性的发展，每个人在稳定转染的CHO细胞中均表达； 2）证明美沙酮的呼吸作用与新生儿猪中的吗啡相似； 3）研究吗啡和美沙酮对子宫内豚鼠新生儿的脑干切片中豚鼠的影响； 4）从豚鼠新生儿NTS中定量MOR mRNA，暴露于子宫内的吗啡和美沙酮。这些研究将提供有关子宫阿片类药物慢性暴露后豚鼠NTS MOR的发展信息。