P450 Epoxygenase Mechanisms of Opioid Analgesia

P450 环氧合酶阿片类药物镇痛机制

• 批准号: 8029585
• 负责人: LINDSAY HOUGH
• 金额: $ 33.45万
• 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/8029585
• 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 mu 阿片受体，产生显着的疼痛缓解作用，但 mu 相关的副作用（包括耐受性和药物滥用）限制了其使用，尽管有大量有关 mu 信号传导的信息，但它的用途仍然有限。吗啡激活脑干镇痛回路的机制仍不清楚，该提案的目的是验证吗啡镇痛的新机制，并研究可能模仿吗啡作用但缺乏副作用的新镇痛剂。细胞色素 P450 是药物代谢酶家族，许多 P450 具有花生四烯酸 (AA) 环氧化酶活性，即将 AA 转化为环氧二十碳三烯酸 (EET)。文献综述中，提出了阿片类药物对脑干镇痛作用的环氧化酶假说： 吗啡 -> ¿受体 -> ? (P450) -> ? EET -> ? 验证和利用这一假设的实验包括：1) 初步研究表明，新开发的大脑 P450 缺陷转基因小鼠 (BCPRN) 具有缺陷的吗啡镇痛表型，为了验证这种阿片类镇痛表型，用 BCPRN 和对照小鼠进行吗啡实验将调查其重要性。吗啡剂量、给药途径、伤害性测试和性别 2) P450 环氧化酶抑制剂可阻断吗啡的镇痛作用。吗啡作用于腹外侧导水管周围灰质、头端腹内侧延髓和脊髓背角，将 P450 抑制剂和吗啡显微注射到大鼠中枢神经系统的这些区域将识别 P450 相关位点，将吗啡显微注射到 BCPRN 和对照小鼠中将识别类似的 P450 相关位点。 3) 证实吗啡的 mu 介导的副作用包括呼吸调节，在大鼠中使用吗啡和 P450 抑制剂以及在 BCPRN 小鼠中使用吗啡进行的实验将发现哪些副作用利用了 P450 机制 4) 在使用 P450 抑制剂和 EET 代谢抑制剂的大鼠中进行了其他实验。将进一步证实和表征 P450 氧化酶在吗啡镇痛中的作用 5) 试验结果表明 EETs 的产物。 AA 环氧化、具有镇痛特性的实验验证 EET 镇痛作用、寻找 EET 副作用以及表征 EET 机制可能会揭示 EET 是一类新型实验性镇痛剂。拟议的研究将增进对吗啡机制的了解。缓解疼痛并产生不良副作用 环氧化酶假说的证实可能会导致开发非阿片类、非成瘾性止痛药的新方法。 公共卫生相关性： 迫切需要发现缺乏成瘾特性的新型止痛药，该提案将揭示新的止痛生化机制，并测试一组新的止痛化学物质。新的、非成瘾性止痛药。