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）：外周神经损伤后，背根（DRG）神经元中两种四氢生物蝶呤（BH 4）合成酶（GTP环化水解酶1（GCH 1）和sepiapterin还原酶）以及BH 4再循环酶醌式二氢蝶啶还原酶的转录物上调。这种诱导与DRG中BH 4的增加有关。BH 4是芳香胺羟化酶和所有一氧化氮合酶的必需辅因子，所述芳香胺羟化酶产生5-羟色胺、去甲肾上腺素和多巴胺。通过全身给予GCH 1抑制剂二氨基羟基嘧啶（DAHP）来预防神经损伤诱导的BH 4增加。DAHP在幼年动物中没有镇痛作用，但在具有外周神经损伤和炎症的啮齿动物中产生疼痛相关行为的显著减少。鞘内注射BH 4本身产生急性疼痛超敏反应。使用单核苷酸多态性分析，我们还确定了人类GCH 1的单倍型，该单倍型在慢性背痛手术后的患者中具有疼痛保护作用，并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BH 4有助于神经性疼痛和炎性疼痛的启动和维持。本提案的目的是：1.研究疼痛相关啮齿动物模型中BH 4诱导在DRG中发生的位置和时间以及何种刺激负责，2。表征成年初级感觉神经元中GCH 1选择性缺失、抑制或过表达的行为后果，以及3.识别BH 4产生疼痛的感觉神经元机制。我们将研究响应于组织炎症和部分周围神经损伤（目的1）的DRG中BH 4合成和再循环酶的表达和活性变化的时间过程和细胞定位。为了阐明BH 4在感觉神经元中的特定作用，我们将采用选择性过表达或在成年初级传入中缺失GCH 1的小鼠，以及过表达GCH 1的内源性抑制剂GFRP的小鼠，使用他莫昔芬诱导的DRG神经元特异性Cre重组酶技术（Aim 2）。nNOS的上调与BH 4的增加有关，我们将测试BH 4是否通过产生NO和钙内流的增加而产生疼痛。我们将使用DRG神经元的原代培养物来探索BH 4对这些神经元的直接作用和下游效应器。该提案旨在探索负责疼痛的分子机制，并确定开发新镇痛药的新靶点。相关性：由于病人遭受痛苦和社会付出高昂的经济代价，持续疼痛是一个巨大的问题。由于目前的治疗通常无效或与不良副作用有关，因此需要更有效的镇痛剂。该基金旨在了解疼痛的机制，并验证一种特殊的酶GCH 1作为开发新型镇痛药的靶点。