Development of a mechanical nociceptive sensitization model in Drosophila

描述(申请人提供)：疼痛敏感化是对组织损伤的一种适应性反应，因为它促进了在损伤愈合时保护损伤部位的行为。敏化可以发生在多种感觉方式，如热和机械，并可表现为对先前的非伤害性刺激的反应(超敏)或对伤害性刺激的夸大反应(痛觉过敏)。我的实验室一直在模拟果蝇幼虫伤害性敏化的热模式，因为这种模式的精确定量分析已经发展和完善。然而，在临床上，组织创伤、手术或在各种疾病状态下导致慢性疼痛(如癌症和糖尿病)后的机械超敏反应是一个比热模式更严重的问题。这是因为患者在日常生活中更常遇到机械刺激。我们在R21提案中的目标是开发分析方法和工具，并为该领域开始解剖果蝇的机械性疼痛过敏症提供足够的基本遗传深度。我们的指导性假设是，有保守的分子遗传机制启动、调节、执行和终止机械性伤害性敏感化。我们开发了适用于测试果蝇幼虫机械伤害性反应的定制Von Frey纤维，定义了这些动物的精确伤害范围，并证明了紫外线诱导的组织损伤后存在机械性超敏和痛敏。此外，在一个小规模的飞行员屏幕上，我们已经确定了机械伤害性感受所需的少量基因。我们的项目目标列举在以下具体目标中：1.测试特定类型的组织损伤(物理损伤、烧伤、化疗)更容易诱发机械性伤害性超敏的假设。2.检验机械伤害性超敏反应与热伤害性超敏反应使用相同的诱导信号的假设。以及，3.鉴定机械伤害敏感化所需的新基因。该项目代表了在模式遗传有机体中对机械伤害敏感性的第一次系统研究，并在揭示启动、执行和调节这一过程的基因方面具有巨大的潜力。它使用了一个模板，我们已经在研究热伤害敏化的方法中成功使用了这个模板。考虑到大多数基本神经功能所需的基因的保守性，我们预计这个项目将有助于我们理解脊椎动物以及癌症、糖尿病和慢性疼痛综合征等病理生理状态下的机械伤害性敏化，在这些状态下，这种形式的感觉神经元可塑性被认为被不适当地激活或调节。

DESCRIPTION (provided by applicant): Pain sensitization is an adaptive response to tissue injury because it fosters behaviors that protect the site of injury while it heals. Sensitization cn occur across multiple sensory modalities such as thermal and mechanical and can manifest as responsiveness to previously non-noxious stimuli (allodynia) or exaggerated responsiveness to noxious stimuli (hyperalgesia). My laboratory has been modeling the thermal mode of nociceptive sensitization in Drosophila larvae since precise quantitative assays for this mode have been developed and refined. Clinically, however, mechanical hypersensitivity following tissue trauma, surgery, or in a variety of disease states that cause chronic pain (such as cancer and diabetes) is a more serious problem than the thermal mode. This is because patients encounter mechanical stimulation much more commonly in the course of daily life. Our goal in this R21 proposal is to develop the assays and tools and a sufficient basic genetic depth of understanding for the field to begin to dissect mechanical pain hypersensitivity in Drosophila. Our guiding hypothesis is that there is conserved molecular genetic machinery that initiates, regulates, executes, and terminates mechanical nociceptive sensitization. We have developed customized Von Frey filaments suitable for testing mechanical nociceptive responses in Drosophila larvae, have defined the precise noxious range for these animals, and have demonstrated the existence of mechanical allodynia and hyperalgesia following UV-induced tissue injury. Further, in a small-scale pilot screen we have identified a small number of genes required for mechanical nociception. Our project goals are enumerated in the following specific aims: 1. To test the hypothesis that particular types of tissue damage (physical wounding, burns, chemotherapy) are more potent at inducing mechanical nociceptive hypersensitivity. 2. To test the hypothesis that mechanical nociceptive hypersensitivity uses the same inducing signals as thermal nociceptive hypersensitivity. And, 3. To characterize novel genes required for mechanical nociceptive sensitization. This project represents the first systematic study of mechanical nociceptive sensitization in a model genetic organism and has great potential for uncovering the genes that initiate, execute, and regulate this process. It uses a template that we have already used successfully in our approach to studying thermal nociceptive sensitization. Given the conservation of genes required for most fundamental neuronal functions we expect that this project will inform our understanding of mechanical nociceptive sensitization in vertebrates and in pathophysiological states, such as cancer, diabetes, and chronic pain syndromes, where this form of sensory neuron plasticity is thought to be improperly activated or regulated.