Dissecting the Molecular Mechanisms of Cold Nociception in Drosophila Larvae

描述（由申请人提供）：糖尿病、癌症、复杂性局部疼痛综合征和其他小纤维神经病患者经常因外周神经损伤而对无害热刺激产生疼痛和适应不良感知。这些疾病状态的这种不幸的症状可能严重影响患者的日常生活，并且在化疗的情况下，可能危险地限制处方有效剂量的能力。有害热感知的分子机制已经相当清楚，但有害冷检测和处理的基本机制却不能这么说，这在很大程度上是未探索的。因此，本研究试图以遗传学上易处理的果蝇为模式生物，来确定有害冷感知的遗传基础。果蝇已经成为发现有害热感知所需的新保守基因的有利模型。在响应于局部施加的高温探针，幼虫表现出强大的螺旋状滚动行为，这是依赖于瞬时受体电位（TRP）通道和幼虫表皮下的特定类别的多树突感觉神经元。还表明，这种反应在组织损伤后是敏感的，需要特定的途径。为了评估有害冷的分子和遗传基础，并确定与有害热通路的同源性程度，设计了一种新型低温探针以创建用于冷伤害感受的测定。该提案的初步数据显示，果蝇幼虫产生了一系列行为反应，这些反应不同于对有害热量和粗糙触摸的滚动反应。这些行为发生在大约75%的野生型幼虫中，并且是一致的和可重复的。根据以往的工作与有害的热和明显不同的行为反应观察到有害的冷刺激，我们假设一个单独的，特定的类的多树突感觉神经元和离子通道所需的感知有害的冷，这种反应是敏感的组织损伤利用已知的途径。本申请中提出的实验将鉴定果蝇幼虫中冷伤害感受所需的特定细胞和途径，从而进一步深入了解冷伤害感受领域和开发治疗方法。

DESCRIPTION (provided by applicant): Patients with diabetes, cancer, complex regional pain syndrome, and other small fiber neuropathies often experience painful and maladaptive perception of innocuous thermal stimuli due to peripheral nerve damage. This unfortunate symptom of these disease states can severely impact the patient's daily life, and in the case of chemotherapy, can dangerously limit the ability to prescribe the effective dose. The molecular mechanisms of noxious heat perception is fairly well understood, but the same cannot be said for the basic mechanisms of noxious cold detection and processing, which is largely unexplored. Therefore, this proposal seeks to determine the genetic basis for noxious cold perception using the genetically tractable Drosophila as a model organism. Drosophila have already lent themselves as an advantageous model for discovering novel conserved genes required for noxious heat perception. In response to a locally applied high temperature probe, larvae exhibit a robust corkscrew-like rolling behavior, which is dependent on transient receptor potential (TRP) channels and a specific class of multidendritic sensory neurons under the larval epidermis. It has also been shown that this response is sensitized following tissue damage, requiring specific pathways. To assess the molecular and genetic basis for noxious cold, and to determine the extent of homology with noxious heat pathways, a novel low temperature probe was engineered to create an assay for cold nociception. The proposal's preliminary data shows Drosophila larva produce a set of behavioral responses that are distinct from the rolling response to noxious heat and harsh touch. These behaviors occur in approximately 75% of wild type larvae, and are consistent and reproducible. Based on previous work with noxious heat and the distinctly different behavioral responses observed to noxious cold stimuli, we hypothesize a separate, specific class of multidendritic sensory neurons and ion channels are required for the perception of noxious cold, and that this response is sensitized following tissue damage utilizing known pathways. The experiments proposed in this application will identify the specific cells and pathways required for cold nociception in Drosophila larvae, allowing further insight into the fiel of cold nociception and development of therapeutics.