Dissecting the Molecular Mechanisms of Cold Nociception in Drosophila Larvae

描述(申请人提供)：糖尿病、癌症、复杂区域疼痛综合征和其他小纤维神经病的患者通常会因周围神经损伤而对无害的热刺激产生痛苦和适应不良的感觉。这些疾病状态的这种不幸症状可能会严重影响患者的日常生活，在化疗的情况下，可能会危险地限制开出有效剂量的能力。对有害的热感觉的分子机制已经相当了解，但对于有害的冷检测和处理的基本机制就不能说了，这在很大程度上是未知的。因此，这项建议试图以遗传上易驯化的果蝇作为模式生物来确定有害冷感的遗传基础。果蝇已经将自己作为发现有害热感知所需的新的保守基因的有利模型。在局部施加高温探头后，幼虫表现出强烈的螺旋状滚动行为，这依赖于瞬时受体电位(Trp)通道和幼虫表皮下特定类型的多树突状感觉神经元。研究还表明，这种反应是在组织损伤后敏化的，需要特定的途径。为了评估伤害性寒冷的分子和遗传基础，并确定与伤害性热途径的同源性程度，设计了一种新型的低温探针，以建立一种寒冷伤害性感受的检测方法。该提案的初步数据显示，果蝇幼虫会产生一系列不同于对有毒高温和刺激性触摸的滚动反应的行为反应。这些行为发生在大约75%的野生型幼虫身上，并且是一致的和可重复的。基于以前对伤害性热的研究和观察到的对伤害性冷刺激的明显不同的行为反应，我们假设感受伤害性冷需要一类单独的、特定的多树突状感觉神经元和离子通道，这种反应是利用已知的途径在组织损伤后敏化的。本申请中提出的实验将确定果蝇幼虫寒冷伤害性感受所需的特定细胞和途径，从而进一步深入了解寒冷伤害性感受领域和治疗方法的发展。

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.