神经病理性疼痛治疗药物的研究进展

神经病理性疼痛治疗药物的研究是目前药物设计及研究领域的热点和难点之一。本文对目前临床应用及正在研究中的、作用机制不同的及疗效较好的治疗神经病理性疼痛的药物类型及其适应证等作了综述，并对当前的研究现状及趋势作一展望。     

神经病理性疼痛的研究进展

本文从神经病理性疼痛的动物模型、发病机制、临床用药3个方面叙述了神经病理性疼痛的研究进展。     

神经病理性疼痛动物模型

神经病理性疼痛动物模型的不断发展极大地促进了对神经病理性疼痛机制的研究。但是,目前的动物模型仍有很多缺陷,需要不断地完善,对疼痛的观察方法也需要改进。     

神经病理性疼痛的药物治疗研究进展

神经病理性疼痛是一种神经系统损伤引起的慢性疼痛,严重影响患者的生活质量。药物治疗仍是现用治疗神经病理性疼痛的主要方法。本文综述了现用于治疗神经病理性疼痛主要药物的分子药理机制及其临床运用特点,并在总结疼痛的发生机制的基础上对靶向治疗药物的研发进行了展望。     

环氧合酶在神经病理性疼痛中作用的研究进展

环氧合酶(COX)是前列腺素(PG)合成的限速酶，至今已发现其至少具有三个亚型：COX-1，COX-2及COX-3。神经病理性疼痛是由于外周或中枢神经系统的直接损伤和功能紊乱而引起的疼痛，其发病机制不明，缺乏有效治疗措施。COX抑制剂已在炎性疼痛治疗方面得到了广泛应用，但其在神经病理性疼痛的治疗中尚处于起步阶段。研究表明，PG特别是脊髓所产生的PG，作为致痛物质在神经病理性疼痛中起作用。虽然COX-2在中枢的表达较COX-1强得多，但两者在神经病理性疼痛中的地位都不容忽视。前者在神经病理性疼痛的早期发展中起主要作用，而后者与神经病理性疼痛的维持有关。COX抑制剂可能通过减少PG的合成或改变神经病理性疼痛后中枢可塑性和敏感性等途径而起到治疗神经病理性疼痛的作用。     

细胞因子参与EPO预防神经病理性疼痛的机制探讨

目的 探讨预防性给予重组人红细胞生成素(rhEPO)对神经病理性疼痛大鼠模型机械、热痛觉高敏的影响及可能的机制.方法 雄性SD大鼠30只随机均分成三组.A、B组切断L5脊神经建立大鼠神经病理性疼痛模型;C组为假手术对照.术前1d,A组腹腔注射rhEPO 5000 U/kg,连续7d;B组腹腔注射生理盐水作为模型对照.采用von Frey仪测定各组0、3和7d机械缩足反射阈值;术后第7天用ELISA法测定大鼠L5脊髓组织TNF-α、IL-1β、IL-6和IL-10表达.结果 与C组相比,A、B组大鼠L5脊神经损伤术后,术侧均出现明显的机械痛阈下降(P＜0.01);但A组大鼠的机械痛高敏行为较B组明显缓解(P＜0.01).与C组比较,大鼠脊髓TNF-α、IL-1β、IL-6和IL-10表达明显增高(P＜0.01);与B组比较,A组脊髓组织IL-6水平明显降低,而IL-10水平明显升高(P＜0.01).结论 rhEPO能预防模型大鼠神经病理性疼痛的发生,其效应与减少促炎细胞因子和增加抗炎细胞因子释放有关.     

神经病理性疼痛动物模型及其评价

对神经病理性疼痛发病机制的研究大多来源于动物模型；尽管模型还存在不少缺点，但是它为理解和探索人类神经病理性疼痛的发病机制提供了有用的工具。动物模型的缺点是动物无法语言交流，对动物的疼痛测量多基于主观行为反应，比如测量痛敏和异常痛敏。最常用的动物模型包括坐骨神经慢性压迫模型和坐骨神经部分损伤模型等，通过测量神经损伤侧肢体脚爪皮肤的感觉阈值即主要通过测评对热、机械刺激痛敏(hyperalgesia)和冷、触异常痛敏(allodynia)来确定模型是否成功。     

川芎嗪对P2X_3受体介导的神经病理痛的作用研究

目的探讨川芎嗪(tetramethylpyrazine,TMP)对P2X3受体介导的神经病理痛的作用。方法建立大鼠坐骨神经慢性压迫性损伤(CCI)神经病理痛模型,应用vonFrey细丝法和热辐射法测定机械缩足反射阈值(mechanical withdrawal threshold,MWT)和热缩足反射潜伏期(thermal withdrawal latency,TWL),观察川芎嗪对CCI大鼠MWT和TWL的影响。结合免疫组织化学方法观察大鼠L4/L5段脊髓P2X3受体的表达变化。结果术后14d,Ⅴ组(CCI模型组)和Ⅰ组(生理盐水对照组)、Ⅱ组(TMP对照组)、Ⅲ组(假手术组)、Ⅳ组(CCI模型+TMP治疗组)相比较大鼠后爪的机械和热痛敏阈值明显降低(P<0.05),大鼠脊髓P2X3受体表达明显升高(P<0.05);Ⅰ、Ⅱ、Ⅲ、Ⅳ组之间相比大鼠后爪的机械和热痛敏阈值差异没有显著性(P>0.05),大鼠脊髓P2X3受体表达差异没有显著性(P>0.05);Ⅳ组脊髓P2X3受体的表达较Ⅴ组低(P<0.05)。结论川芎嗪对P2X3受体介导的神经病理痛有抑制作用。     

神经病理性疼痛的药物治疗进展

神经病理性疼痛(NPP)是由一系列感染和神经损伤事件引起的慢性疼痛,其发病率高、病因复杂,严重影响患者的生活质量。尽管临床试验逐渐增多,但NPP的治疗仍存在不足。合理使用不同作用机制和持续时间的药物,是当前治疗NPP的研究热点。针对近年来NPP的药物治疗进展做一总结,为该病的治疗提供依据。     

神经痛的药物作用靶点及其机制

目的对近年来出现的治疗神经痛的药物作用靶点及其机制作以综述。方法在查阅30篇文献的基础上,对神经痛的治疗靶点进行整理和归纳。结果目前治疗神经痛的药物作用靶点主要有5-羟色胺受体、去甲肾上腺素受体、阿片受体、大麻素受体、离子通道、免疫相关物质等等。以这些靶点设计的药物均已证明可在一定程度上缓解神经痛。结论为进一步开发治疗神经痛的靶向药物提供参考。     

GABA and central neuropathic pain following spinal cord injury

Spinal cord injury induces maladaptive synaptic transmission in the somatosensory system that results in chronic central neuropathic pain. Recent literature suggests that glial-neuronal interactions are important modulators in synaptic transmission following spinal cord injury. Neuronal hyperexcitability is one of the predominant phenomenon caused by maladaptive synaptic transmission via altered glial-neuronal interactions after spinal cord injury. In the somatosensory system, spinal inhibitory neurons counter balance the enhanced synaptic transmission from peripheral input. For a decade, the literature suggests that hypofunction of GABAergic inhibitory tone is an important factor in the enhanced synaptic transmission that often results in neuronal hyperexcitability in dorsal horn neurons following spinal cord injury. Neurons and glial cells synergistically control intracellular chloride ion gradients via modulation of chloride transporters, extracellular glutamate and GABA concentrations via uptake mechanisms. Thus, the intracellular “GABA-glutamate-glutamine cycle” is maintained for normal physiological homeostasis. However, hyperexcitable neurons and glial activation after spinal cord injury disrupts the balance of chloride ions, glutamate and GABA distribution in the spinal dorsal horn and results in chronic neuropathic pain. In this review, we address spinal cord injury induced mechanisms in hypofunction of GABAergic tone that results in chronic central neuropathic pain.This article is part of a Special Issue entitled ‘Synaptic Plasticity & Interneurons’.     

Emerging drugs in neuropathic pain

Neuropathic pain is a personally devastating and costly condition affecting 3 – 8% of the population. Existing treatments have limited effectiveness and produce relatively frequent adverse effects. Preclinical research has identified many promising pharmacological targets; however, reliable predictors of success in humans remain elusive. At least 50 new molecular entities have reached clinical development including: glutamate antagonists, cytokine inhibitors, vanilloid-receptor agonists, catecholamine modulators, ion-channel blockers, anticonvulsants, opioids, cannabinoids, COX inhibitors, acteylcholine modulators, adenosine receptor agonists and several miscellaneous drugs. Eight drugs are in Phase III trials at present. Strategies that may show promise over existing treatments include topical therapies, analgesic combinations and, in future, gene-related therapies. Recent years have heralded an explosion of pharmaceutical development in neuropathic pain, reflecting advanced knowledge of neurobiology and a heightened perception of the commercial value of neuropathic pain therapeutics. In the interest of improving patient care, the authors recommend implementing comparative studies throughout the development process in order to demonstrate the increased value of novel agents.     

Modulation of benzodiazepine receptor binding: insight into pharmacological efficacy

The effects of GABA on the binding of analogues of benzodiazepines, triazolopyridazines, beta-carbolines and imidazodiazepines were examined in ligand/[3H] flunitrazepam competition experiments. GABA increased the potency of anxiolytics, like flunitrazepam, whereas the potency of benzodiazepine antagonists, like Ro15-1788, was largely insensitive to the influence of GABA. Several other agents including pyrazolopyridines, barbiturates and etomidate caused a chloride dependent enhancement of [3H] flunitrazepam binding but not an enhancement of [3H] propyl-beta-carboline-3-carboxylate binding.     

New investigational drugs for the treatment of neuropathic pain

Introduction: Neuropathic pain (NP) is a chronic condition that arises from a lesion or dysfunction of the somatosensory nervous system. However, there are several new targets and novel technologies in the pipeline to address this unmet medical need.

Areas covered: In this review, the authors briefly discuss a direction of the development of agents that could be potentially used in NP treatment. Special attention is paid to 1.7-selective voltage-gated sodium channels, N-type voltage-gated calcium channels, angiotensin II (Ang II) AT₂ receptors and nerve growth factor (NGF) as promising targets for new drugs. Furthermore, the article also presents and discusses, in detail, the results of Phase II clinical studies with the AT₂ receptor antagonist ? EMA401 in NP (the results of Phase II clinical trials of other described compounds are not available, yet).

Expert opinion: There is a real hope that new drugs for NP may be available soon. This hope is based on advancing methods of genomics, developing new targets and more efficient drug screening. Some forms of direct influence on voltage-gated ion channels have a place in the treatment of NP, while the development of entirely novel Ang II AT₂ receptor antagonists or NGF inhibitors may be available for many chronic pain sufferers in the foreseeable future.     

Interaction of benzodiazepine receptor agonists and inverse agonists with the GABA benzodiazepine receptor complex

The effects of the benzodiazepine receptor agonists, antagonists and inverse agonists on the in vitro binding of several ligands which label different recognition sites of the GABA benzodiazepine receptor complex are summarized. Also, results with a novel biochemical in vitro functional model of the GABA benzodiazepine receptor complex are presented. They are compatible with the concept that drugs which act on benzodiazepine receptors can lead to a bidirectional modulation of the gain of GABAergic neurotransmission.     

Pregabalin in the management of central neuropathic pain

Central neuropathic pain is a painful condition, often severe, that occurs in a person who is already affected by an injury or disease of the brain or spinal cord. This dual insult is especially threatening to the quality of life of a person and their ability to perform even the most basic of tasks. Despite this high level of suffering there are relatively few trials investigating the management of central neuropathic pain. However, two randomised placebo-controlled studies have recently emerged demonstrating efficacy of pregabalin in reducing central neuropathic pain due to spinal cord injury and central poststroke pain. Pregabalin, an anticonvulsant, has been shown to be efficacious in the management of peripheral neuropathic pain of various causes and now may have a role to play in central neuropathic pain.