Morphine tolerance in live neurons

活神经元的吗啡耐受性

• 批准号: 8452833
• 负责人: Erica Sawyer Levitt
• 金额: $ 5.22万
• 依托单位: OREGON HEALTH & SCIENCE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-04-01 至 2014-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8452833
• 关键词: ARRB2; Agonist; Animals; Brain; Cells; Chronic; Clinic; Coupled; Development; Dose; Effectiveness; Electrophysiology (science); Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; Excision; G protein-coupled inwardly-rectifying potassium channel; GTP-Binding Proteins; Goals; Hour; In Vitro; Injection of therapeutic agent; Knockout Mice; Learning; Life; Ligands; Long-Term Effects; Measures; Mediating; Morphine; Mus; Neurons; Okadaic Acid; Opioid; Pain; Patients; Pharmaceutical Preparations; Phosphoric Monoester Hydrolases; Phosphorylation; Potassium; Property; Protein Dephosphorylation; Rattus; Recovery; Regimen; Risk; Role; Signal Transduction; Slice; Testing; Therapeutic; Time; Tissues; Work; addiction; arrestin 2; chronic pain; clinically relevant; desensitization; locus ceruleus structure; mu opioid receptors; novel therapeutics; phosphatase inhibitor; prevent; receptor; research study; response; voltage clamp

DESCRIPTION (provided by applicant): Morphine is one of the most commonly prescribed opioids to treat pain. However, prolonged use often leads to the development of tolerance characterized by loss of effectiveness and dose escalation. Morphine tolerance is in part due to a loss of signaling from mu opioid receptors (MOR) independent of a change in receptor levels. Despite years of study, the mechanisms causing this loss of signaling remain unsolved. Traditionally, tolerance is measured in cells or tissue removed from a chronically treated animal and washed free of morphine for several hours. Preliminary experiments have discovered that if brain slices from a morphine-treated rat are instead maintained in morphine continuously, the morphine response is significantly smaller compared to slices in which morphine was washed out, indicating that a portion of tolerance can recover within a relatively short wash. This rapid recovery following morphine removal is newly identified and may have appreciable importance to the persistence of tolerance. The goal of this proposal is to better understand morphine tolerance by carefully examining the often overlooked desensitization that is maintained by the continuous presence of morphine. The overall hypothesis is that two types of tolerance (long-lasting tolerance and chronic desensitization) develop during long-term morphine treatment distinguished by the time-course of recovery, which have different mechanisms and depend on treatment paradigm. This hypothesis will be tested using locus coeruleus neurons contained in brain slices from naove or morphine-treated animals. Morphine effects will be measured using whole-cell voltage-clamp electrophysiology to detect MOR-mediated activation of G protein-coupled inwardly rectifying potassium (GIRK) channels. The specific aims of this proposal are as follows: (1) to identify the long-lasting tolerance and chronic desensitization that results from long-term continuous morphine treatment of rats and mice, (2) to compare this to tolerance and desensitization following long-term intermittent morphine treatment and (3) to determine the role of 2-arrestin 2 in the development of long-lasting tolerance (using 2-arrestin 2 knockout mice) and the role of ser/thr phosphatases in development of and recovery from chronic desensitization (using okadaic acid). Together, this proposal will provide new information about chronic desensitization that develops after long-term morphine treatment. Focusing on morphine specifically will help identify mechanisms involved in tolerance to this most commonly used opioid agonist.

描述（由申请人提供）：吗啡是治疗疼痛的最常见的阿片类药物之一。但是，延长使用通常会导致耐受性的发展，其特征是丧失有效性和剂量升级。吗啡耐受性部分是由于与受体水平变化无关MU阿片受体（MOR）的信号传导损失。尽管进行了多年的研究，但导致这种信号损失的机制仍未解决。传统上，耐受性是在从长期处理的动物中去除的细胞或组织中测量的，并没有吗啡洗涤几个小时。初步实验发现，如果持续将来自吗啡处理的大鼠的大脑切片保持在吗啡中，则与将吗啡洗净的切片相比，吗啡反应要小得多，表明一部分耐受性可以在相对短的洗涤中恢复。新确定的吗啡去除后这种快速恢复，可能对宽容的持续存在很重要。该提案的目的是通过仔细检查吗啡的持续存在来更好地理解吗啡耐受性。总体假设是在长期吗啡治疗期间出现了两种类型的耐受性（持久的耐受性和慢性脱敏），这些耐受性通过恢复时间的恢复时间来区分，它们具有不同的机制，并取决于治疗范式。该假设将使用NAOVE或吗啡治疗动物的脑切片中包含的基因座神经元进行检验。将使用全细胞电压钳电生理学测量吗啡效应，以检测MOR介导的G蛋白偶联的内部整流钾（GIRK）通道的激活。该提议的具体目的如下：（1）确定长期连续的吗啡治疗大鼠和小鼠的持续耐受性和慢性脱敏，（2）将其与长期间歇性的吗啡治疗和（3）在2-敲击中的作用（3）的作用（3）在长期间歇性治疗后进行比较（2）。 Ser/THR磷酸酶在慢性脱敏（使用冈田酸）中的发展和恢复中的作用。该提案一起将提供有关长期吗啡治疗后发展的慢性脱敏的新信息。专门针对吗啡将有助于确定对这种最常用的阿片类药物激动剂的耐受性涉及的机制。