P450 Epoxygenase Mechanisms of Opioid Analgesia

P450 环氧合酶阿片类药物镇痛机制

• 批准号: 8234084
• 负责人: LINDSAY HOUGH
• 金额: $ 29.81万
• 依托单位: ALBANY MEDICAL COLLEGE
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-03-01 至 2015-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8234084
• 关键词: Absence of pain sensation; Acids; Adverse effects; Agonist; Analgesics; Arachidonic Acids; Area; Biochemical; Biological; Body Temperature; Brain; Brain Stem; Characteristics; Complement; Cytochrome P450; Cytochromes; Data; Development; Dose; Enzymes; Family; Gender; Goals; Inflammatory; Isomerism; Knockout Mice; Lead; Measurement; Measures; Mechanics; Mediating; Metabolic; Metabolism; Microinjections; Morphine; Motor Activity; Mus; NADPH-Ferrihemoprotein Reductase; Neurons; Nociception; Opioid; Opioid Analgesics; Opioid Receptor; Pain; Performance; Pharmaceutical Preparations; Phenotype; Pilot Projects; Property; Protein Isoforms; Rattus; Research; Respiration; Review Literature; Role; Route; Signal Transduction; Site; Spinal; Spinal Cord; Substance abuse problem; System; Testing; Transgenic Mice; Wild Type Mouse; base; chemical group; dorsal horn; inhibitor/antagonist; midbrain central gray substance; mu opioid receptors; novel strategies; oxidation; public health relevance; receptor; research study; respiratory; response

DESCRIPTION (provided by applicant): Morphine acts on mu opioid receptors in the brain and spinal cord to produce dramatic pain relief, but mu-associated side effects (including tolerance and substance abuse) limit its use. Despite substantial information on mu signaling, the mechanisms by which morphine activates brain stem analgesic circuits remain unknown. The goal of this proposal is to validate a new mechanism for morphine analgesia and to investigate new analgesic agents which may mimic morphine actions but lack side effects. Cytochrome P450s are a family of drug-metabolizing enzymes that also perform endogenous metabolic oxidations in the brain. Many P450s have arachidonic acid (AA) epoxygenase activity, i.e. they convert AA to epoxyeicosatrienoic acids (EETs). Based on three new findings and a literature review, an epoxygenase hypothesis is proposed for opioid analgesic action in the brain stem: Morphine -> ¿ receptor -> ? AA -> (P450) -> ? EET s -> ? K+ -> ? Analgesic Circuits Experiments to validate and exploit this hypothesis include: 1) Pilot studies show that newly-developed brain P450-deficient transgenic mice (BCPRN) have defective morphine antinociception. To validate this opioid analgesic phenotype, morphine experiments with BCPRN and control mice will investigate the importance of morphine dose, routes of administration, nociceptive tests and gender. 2) P450 epoxygenase inhibitors block morphine antinociception. Since morphine acts in the ventrolateral periaqueductal gray, the rostral ventromedial medulla, and the spinal dorsal horn, microinjections of P450 inhibitors and morphine into these regions of the rat CNS will identify the P450-relevant sites. Similar microinjections of morphine into BCPRN and control mice will confirm results from rats. 3) Morphine's mu-mediated side effects include modulation of respiration, locomotor activity, rotorod performance, and body temperature. Experiments with morphine and P450 inhibitors in rats and with morphine in BCPRN mice will discover which of these side effects utilize P450 mechanisms. 4) Additional experiments in rats with P450 inhibitors and with inhibitors of EET metabolism will further confirm and characterize the role of P450 expoxygenases in morphine analgesia. 5) Pilot results show that EETs, the products of AA epoxidation, have antinociceptive properties. Experiments to validate EET analgesia, to search for EET side effects, and to characterize EET mechanisms may reveal EETs to be a new class of experimental analgesic agents. The proposed studies will increase understanding of the mechanisms by which morphine relieves pain and produces unwanted side effects. Confirmation of the epoxygenase hypothesis may lead to new approaches for developing non-opioid, non-addicting pain relievers. PUBLIC HEALTH RELEVANCE: There is an urgent need to discover new kinds of pain-relievers that lack addictive properties. This proposal will uncover new biochemical mechanisms for pain relief, and test a new group of chemicals for pain-relieving properties. This research could lead to the development of new, non-addicting pain relievers.

描述（由申请人提供）：吗啡作用于大脑和脊髓中的μ阿片受体，以产生显著的疼痛缓解，但μ相关的副作用（包括耐受性和药物滥用）限制了其使用。尽管有大量关于mu信号的信息，吗啡激活脑干镇痛回路的机制仍然未知。本研究的目的是验证吗啡镇痛的新机制，并研究新的镇痛剂，可以模拟吗啡的作用，但没有副作用。细胞色素P450是一个药物代谢酶家族，也在大脑中进行内源性代谢氧化。许多P450具有花生四烯酸（AA）环氧合酶活性，即它们将AA转化为环氧二十碳三烯酸（ECO 2）。基于三项新发现和文献综述，提出了脑干阿片类镇痛作用的环氧合酶假说： 吗啡受体AA ->（P450）->？EET s ->？K+ ->？镇痛回路 验证和利用这一假说的实验包括：1）初步研究表明，新开发的脑P450缺陷型转基因小鼠（BCPRN）具有缺陷的吗啡抗伤害感受。为了验证这种阿片类镇痛表型，使用BCPRN和对照小鼠的吗啡实验将研究吗啡剂量、给药途径、伤害感受试验和性别的重要性。2)P450环氧酶抑制剂阻断吗啡镇痛作用。由于吗啡作用于中脑导水管周围灰质腹外侧、延髓头端腹内侧和脊髓背角，因此将P450抑制剂和吗啡微量注射到大鼠CNS的这些区域中将识别P450相关位点。对BCPRN和对照小鼠进行类似的吗啡微量注射将证实大鼠的结果。3)吗啡的μ-介导的副作用包括调节呼吸、自发活动、旋转棒性能和体温。在大鼠中使用吗啡和P450抑制剂以及在BCPRN小鼠中使用吗啡的实验将发现这些副作用中的哪一个利用P450机制。4)用P450抑制剂和EET代谢抑制剂在大鼠中进行的其他实验将进一步证实和表征P450加氧酶在吗啡镇痛中的作用。5)初步研究结果表明，AA环氧化产物依地平具有镇痛作用。验证EET镇痛，寻找EET副作用，并表征EET机制的实验可能揭示EET是一类新的实验性镇痛剂。这项研究将增加对吗啡缓解疼痛和产生不良副作用的机制的理解。环氧合酶假说的证实可能会导致开发非阿片类药物，非成瘾性止痛药的新方法。 公共卫生相关性： 迫切需要发现新的止痛药，没有上瘾的特性。这项提案将揭示缓解疼痛的新生化机制，并测试一组新的化学物质的缓解疼痛特性。这项研究可能会导致新的，非成瘾性止痛药的开发。