Tetrahydrobiopterin and pain

四氢生物蝶呤与疼痛

• 批准号: 7912421
• 负责人: CLIFFORD J WOOLF
• 金额: $ 8.19万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-01-01 至 2010-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7912421
• 关键词: Absence of pain sensation; Acute Pain; Adult; Adverse effects; Afferent Neurons; Analgesics; Animals; Aromatic Amines; Attenuated; Behavior; Behavioral; Calcium; Calcium Channel; Chronic low back pain; Data; Development; Dopamine; Enzymes; Figs - dietary; GTP Cyclohydrolase; Generations; Grant; Haplotypes; Human; Hypersensitivity; Inflammation; Inflammatory; Knockout Mice; Lesion; Maintenance; Mediator of activation protein; Mixed Function Oxygenases; Modeling; Molecular; Mus; Neurons; Neuropathy; Nitric Oxide; Nitric Oxide Synthase; Norepinephrine; Operative Surgical Procedures; Oxidoreductase; Pain; Partner in relationship; Pathway interactions; Patients; Peripheral; Peripheral Nerves; Peripheral nerve injury; Persistent pain; Phenotype; Production; Protein Isoforms; Proteins; Recycling; Rodent; Rodent Model; Role; Sepiapterin reductase; Serotonin; Single Nucleotide Polymorphism; Societies; Spinal Ganglia; Stimulus; Tamoxifen; Technology; Testing; Time Study; Tissues; Transcript; Transgenic Mice; base; chronic back pain; cofactor; cohort; design; dihydropteridine reductase; economic cost; enzyme activity; experience; inflammatory neuropathic pain; inflammatory pain; inhibitor/antagonist; injured; mutant; nerve injury; novel; overexpression; pain behavior; painful neuropathy; prevent; recombinase; response; selective expression; spinal nerve posterior root; synthetic enzyme; tetrahydrobiopterin

DESCRIPTION (provided by applicant): Transcripts for two tetrahydrobiopterin (BH4) synthetic enzymes, GTP cyclohydrolase 1 (GCH1) and sepiapterin reductase, and a BH4 recycling enzyme quinoid dihydroypteridine reductase, are upregulated in dorsal root (DRG) neurons after peripheral nerve injury. This induction is associated with an increase in BH4 in the DRG. BH4 is an essential cofactor for the aromatic amine hydroxylases that produce 5- hyrdoxytryptamine, norepinephrine and dopamine, and for all nitric oxide synthases. The nerve injury-induced increase in BH4 is prevented by systemic administration of a GCH1 inhibitor, diamino hydroxypyrimidine (DAHP). DAHP has no analgesic effects in naove animals but produces a marked reduction in pain-related behavior in rodents with peripheral nerve lesions and inflammation. Intrathecal BH4 itself produces acute pain hypersensitivity. Using an analysis of single nucleotide polymorphisms we have also identified a haplotype in human GCH1 that is pain protective in patients after surgery for chronic back pain and associated with reduced pain sensitivity in healthy subjects. Based on these data we hypothesize that BH4 contributes to the initiation and maintenance of neuropathic and inflammatory pain. The aim of this proposal is to: 1. Study where and when BH4 induction occurs in the DRG in pain-related rodent models and what kinds of stimuli are responsible, 2. Characterize the behavioral consequences of deletion, inhibition or overexpression of GCH1 selectively in adult primary sensory neurons, and 3. Identify the mechanisms in sensory neurons by which BH4 produces pain. We will study the time course and cellular localization of changes in the expression and activity of BH4 synthetic and recycling enzymes in the DRG in response to tissue inflammation and partial peripheral nerve injury (Aim 1). To elucidate the specific role of BH4 in sensory neurons we will employ mice that selectively overexpress, or have a deletion of GCH1 in adult primary afferents, as well as mice that overexpress the endogenous inhibitor of GCH1, GFRP, using tamoxifen-inducible DRG neuron-specific Cre-recombinase technology (Aim 2). nNOS is upregulated in association with the increase in BH4 and we will test if BH4 produces pain by producing an increase in NO and calcium influx. We will use primary cultures of DRG neurons to explore the direct action of BH4 on these neurons and the downstream effectors responsible. The proposal is designed to explore the molecular mechanisms responsible for pain and identify novel targets for the development of new analgesics. Relevance: Persistent pain is an enormous problem due both to the suffering experienced by patients and the high economic cost to society. Because current therapy is often ineffective or associated with adverse side effects, more efficacious analgesics are required. This grant aims both to understand the mechanisms responsible for pain, and validate a particular enzyme, GCH1, as a target for developing novel analgesics.

描述（由申请人提供）：周围神经损伤后，背根（DRG）神经元中两种四氢生物蝶呤（BH4）合成酶、GTP环化水解酶1（GCH1）和墨蝶呤还原酶以及BH4回收酶醌二氢蝶啶还原酶的转录本上调。这种诱导与 DRG 中 BH4 的增加有关。 BH4 是产生 5-羟色胺、去甲肾上腺素和多巴胺的芳香胺羟化酶以及所有一氧化氮合酶的重要辅助因子。通过全身施用 GCH1 抑制剂二氨基羟基嘧啶 (DAHP) 可以防止神经损伤引起的 BH4 增加。 DAHP 对新手动物没有镇痛作用，但可以显着减少患有周围神经损伤和炎症的啮齿动物的疼痛相关行为。鞘内注射 BH4 本身会产生急性疼痛过敏。通过对单核苷酸多态性的分析，我们还鉴定了人类 GCH1 中的一种单倍型，它对慢性背痛手术后患者的疼痛具有保护作用，并且与健康受试者的疼痛敏感性降低相关。 基于这些数据，我们假设 BH4 有助于神经性疼痛和炎性疼痛的引发和维持。该提案的目的是： 1. 研究疼痛相关啮齿动物模型中 DRG 中何时何地 BH4 诱导发生以及何种刺激负责， 2. 表征选择性删除、抑制或过度表达 GCH1 的行为后果成人初级感觉神经元，以及 3. 确定 BH4 产生疼痛的感觉神经元机制。我们将研究 DRG 中 BH4 合成和回收酶的表达和活性变化的时间过程和细胞定位，以响应组织炎症和部分周围神经损伤（目标 1）。为了阐明 BH4 在感觉神经元中的具体作用，我们将使用在成年初级传入神经中选择性过度表达或缺失 GCH1 的小鼠，以及过度表达 GCH1 内源性抑制剂 GFRP 的小鼠，使用他莫昔芬诱导的 DRG 神经元。特定的 Cre 重组酶技术（目标 2）。 nNOS 的上调与 BH4 的增加相关，我们将测试 BH4 是否通过增加 NO 和钙流入来产生疼痛。我们将使用 DRG 神经元的原代培养物来探索 BH4 对这些神经元和下游效应器的直接作用。该提案旨在探索导致疼痛的分子机制，并确定开发新型镇痛药的新靶点。相关性：由于患者所经历的痛苦和社会的高昂经济成本，持续疼痛是一个巨大的问题。由于目前的治疗通常无效或伴有不良副作用，因此需要更有效的镇痛药。这笔资助的目的是了解疼痛的机制，并验证一种特定的酶 GCH1 作为开发新型镇痛药的目标。