The effect of biased agonism at the Mu-Opioid receptor on drug seeking behavior

Mu-阿片受体的偏向激动对药物寻求行为的影响

• 批准号: 10590603
• 负责人: Lindsey Claire Felth
• 金额: $ 2.22万
• 依托单位: UNIVERSITY OF CALIFORNIA AT DAVIS
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-04-01 至 2023-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10590603
• 关键词: ARRB2; Absence of pain sensation; Adenylate Cyclase; Adverse event; Affect; Agonist; Analgesics; Animal Model; Animals; Arrestins; Automobile Driving; Bar Codes; Biological Assay; Biology; Cell model; Cells; Centers for Disease Control and Prevention (U.S.); Cessation of life; Chronic; Clinic; Clinical; Codeine; Complex; Coupled; Cyclic AMP; Data; Dependence; Development; Dose; Drug Design; Drug Industry; Drug usage; Emergency Situation; Endocytosis; Endorphins; Engineering; Enkephalins; Failure; G Protein-Coupled Receptor Signaling; G-Protein-Coupled Receptors; GTP-Binding Proteins; Glutamic Acid; Goals; Impulsivity; In Vitro; Knock-out; Knockout Mice; Ligands; Mediating; Methadone; Modeling; Morphine; Mus; Mutation; Neuronal Plasticity; Opiate Addiction; Opioid; Opioid Analgesics; Opioid Receptor; Oral; Overdose; Oxycodone; Pain; Pain management; Pathway interactions; Peptides; Persons; Pharmaceutical Preparations; Pharmacology; Phenotype; Phosphorylation; Positioning Attribute; Property; Public Health; Recommendation; Recycling; Regulatory Pathway; Rewards; Risk; Self Administration; Signal Transduction; Signaling Protein; Substance Use Disorder; System; Testing; Threonine; Time; Titrations; Training; United States; Ventilatory Depression; Vicodin; Wild Type Mouse; abuse liability; behavioral plasticity; beta-Endorphin; clinical pain; desensitization; design; drug development; drug seeking behavior; emotional distress; endogenous opioids; in vivo; insight; knockout animal; mimetics; mouse model; mu opioid receptors; mutant; novel; opioid abuse; opioid epidemic; opioid overdose; opioid use; pre-clinical; prevent; protein activation; receptor; recruit; response; side effect; small molecule; trafficking

In 2020, drug overdoses jumped by 30% with 190 people in the United States dying every day from opioid overdose. Despite their significant risks, opioids analgesics, including morphine, codeine, Vicodin and oxycontin, are still regarded as the gold standard for alleviating severe pain. All of these drugs exert their analgesic effects through activation of a G protein coupled receptor (GPCR), specifically the Gi coupled µ- Opioid receptor (MOR). Repeated use of opioids leads to the development of tolerance to the analgesic effects of these drugs. This tolerance necessitates dose escalation to maintain sufficient pain control, which, in turn, increases both the likelihood of adverse events including enhanced respiratory depression and death as well as the liability to develop opioid dependence, manifested as physical and emotional distress in the absence of drug. Importantly, dependence is a key driver of the transition from opioid use to opioid abuse yet there is little understanding of the cellular signaling properties of the MOR that promote this transition. The signaling cascade induced by endogenous opioid ligands, such as beta-endorphin, from the MOR in response provide insight, as they produce analgesia without causing the severe tolerance and dependence observed in response to the small molecule opioid drugs. One key difference between the endogenous and exogenous opioids are their ability to recruit β-arrestin-2 following G-protein activation. Counter-intuitively, the endogenous ligands are better recruiters of β-arrestin-2 and subsequently drive substantially more receptor endocytosis and recycling than opioid drugs, even though they produce less tolerance. As such, we propose that facilitating endocytosis will titrate signal transduction at MOR, emulating endorphin signal transduction, thereby reducing tolerance and dependence. To test this hypothesis, we have manipulated the ‘phosphorylation barcode’ of MOR and created an engineered receptor that recruits β-arrestin-2 and undergoes endocytosis in response to morphine. Here we will thoroughly characterize this mutant receptor in a cell-based model, including a cell- based model of tolerance and dependence. We will also assess the phenotypes of WT and β-arrestin-2-KO mice in response to morphine and methadone, the only small molecule drug that significantly recruits β- arrestin-2. We will assess tolerance and dependence in β-arrestin-2-KO in response to morphine and more importantly, methadone. We will use a novel oral operant self-administration paradigm for 16 weeks to model the transition from impulsive to compulsive drug use in both WT and β-arrestin-2-KO animals. For decades the opioid field has focused, unsuccessfully, on developing drugs that show reduced side effects. We propose that these efforts have failed because they were based on the assumption that recruitment of β-arrestin-2 produces tolerance and dependence. The studies proposed here are designed to provide substantial evidence that recruitment of β-arrestin-2 and subsequent endocytosis and recycling is beneficial. As such, they could inform drug development of novel opioid with reduced abuse liability.

2020 年，美国吸毒过量激增 30%，每天有 190 人死于阿片类药物 过量。尽管存在重大风险，阿片类镇痛药，包括吗啡、可待因、维柯丁和 奥施康定仍被视为缓解剧烈疼痛的金标准。所有这些药物都发挥其作用 通过激活 G 蛋白偶联受体 (GPCR)，特别是 Gi 偶联 µ- 发挥镇痛作用 阿片受体（MOR）。重复使用阿片类药物会导致对镇痛作用产生耐受性 这些药物。这种耐受性需要增加剂量以维持足够的疼痛控制，反过来， 增加不良事件的可能性，包括呼吸抑制加剧和死亡 作为发展阿片类药物依赖的可能性，表现为在没有阿片类药物的情况下身体和情绪上的痛苦 药品。重要的是，依赖性是从阿片类药物使用过渡到阿片类药物滥用的关键驱动因素，但几乎没有 了解促进这种转变的 MOR 的细胞信号传导特性。信令 由 MOR 内源性阿片配体（例如 β-内啡肽）诱导的级联反应提供了 洞察力，因为它们产生镇痛，但不会引起严重的耐受性和依赖性 对小分子阿片类药物的反应。内源性和外源性之间的一个关键区别 阿片类药物具有在 G 蛋白激活后募集 β-arrestin-2 的能力。与直觉相反，内生 配体是 β-arrestin-2 更好的募集者，随后驱动更多的受体内吞作用 回收率高于阿片类药物，尽管它们产生的耐受性较低。因此，我们建议促进 内吞作用会滴定 MOR 的信号转导，模拟内啡肽信号转导，从而减少 耐受和依赖。为了检验这个假设，我们操纵了“磷酸化条形码” MOR 并创建了一种工程化受体，该受体招募 β-arrestin-2 并进行内吞作用以响应 吗啡。在这里，我们将在基于细胞的模型中彻底表征这种突变受体，包括细胞- 基于耐受性和依赖性的模型。我们还将评估 WT 和 β-arrestin-2-KO 的表型 小鼠对吗啡和美沙酮的反应，这是唯一能显着招募 β- 的小分子药物 抑制蛋白-2。我们将评估 β-arrestin-2-KO 对吗啡等的耐受性和依赖性 重要的是，美沙酮。我们将使用一种新颖的口头操作自我管理范式 16 周来建模 WT 和 β-arrestin-2-KO 动物从冲动性用药到强迫性用药的转变。几十年来 阿片类药物领域一直专注于开发副作用减少的药物，但没有成功。我们建议 这些努力都失败了，因为它们基于这样的假设：β-arrestin-2 的募集会产生 耐受和依赖。这里提出的研究旨在提供实质性证据 β-arrestin-2 的募集以及随后的内吞作用和再循环是有益的。因此，他们可以告知 减少滥用可能性的新型阿片类药物的药物开发。