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（由适用提供）：吗啡作用于大脑和脊髓中的MU阿片受体，可产生明显的疼痛缓解，但与MU相关的副作用（包括耐受性和药物滥用）限制了其使用。尽管有关MU信号传导的大量信息，但吗啡激活脑干镇痛电路的机制仍未知。该提案的目的是验证一种新的吗啡镇痛机制，并研究可能模仿吗啡作用但缺乏副作用的新镇痛药。细胞色素P450是一种药物代谢酶家族，在大脑中也执行内源性代谢氧化。许多P450具有花生四烯酸（AA）环氧酶活性，即它们将AA转化为环氧酸性酸（EET）。基于三个新发现和文献综述，提出了在脑干中的阿片类镇痛作用的环氧酶假说： 吗啡 - >¿受体 - >？ AA->（P450） - >？ eet s->？ K+ - >？镇痛电路 验证和利用这一假设的实验包括：1）初步研究表明，新发达的脑P450缺陷转基因小鼠（BCPRN）具有有缺陷的吗啡抗伤害感受。为了验证这种Ooid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，伤害性测试和性别的重要性。 2）P450环氧酶抑制剂阻断吗啡抗伤害感受。由于吗啡作用于腹外侧灰灰色，延髓腹侧髓质和脊髓背角，因此P450抑制剂的显微注射和吗啡将识别大鼠CNS的这些区域，将鉴定出P450相关的位点。吗啡在BCPRN和对照小鼠中的类似显微注射将确认大鼠的结果。 3）吗啡的MU介导的副作用包括调节呼吸，运动活性，Rotorod性能和体温。大鼠中吗啡和P450抑制剂和BCPRN小鼠中吗啡的实验将发现这些副作用中的哪种利用P450机制。 4）在具有P450抑制剂和EET代谢抑制剂大鼠的其他实验将进一步证实并表征P450增生酶在吗啡镇痛中的作用。 5）试点结果表明，EET是AA环氧化的产物具有抗伤害感受特性。验证EET镇痛，寻找EET副作用并表征EET机制的实验可能会表明EET是一类新的实验镇痛药。拟议的研究将增加对吗啡挽救疼痛并产生不必要的副作用的机制的理解。对环氧酶假说的确认可能会导致开发非阿片类药物的新方法。 公共卫生相关性： 迫切需要发现缺乏其他特性的新型止痛药。该建议将发现缓解疼痛的新生化机制，并测试一组新的化学物质用于止痛药。这项研究可能会导致新的，不添加的疼痛缓解。