Dissecting the Molecular Mechanisms of Cold Nociception in Drosophila Larvae

描述（由申请人提供）：患有糖尿病、癌症、复杂局部疼痛综合征和其他小纤维神经病的患者，由于周围神经损伤，通常会对无害的热刺激产生疼痛和不适应的感觉。这些疾病状态的不幸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。毒热感知的分子机制已经被很好地理解，但毒冷探测和加工的基本机制却没有被充分理解。因此，这一建议试图确定有毒寒冷感知的遗传基础，使用遗传易感的果蝇作为模式生物。果蝇已经成为发现有毒热感知所需的新保守基因的有利模型。在局部高温探针的作用下，幼虫表现出强劲的螺旋状滚动行为，这取决于幼虫表皮下的瞬态受体电位（TRP）通道和一类特定的多树突感觉神经元。研究还表明，这种反应在组织损伤后会变得敏感，需要特定的途径。为了评估毒寒的分子和遗传基础，并确定与毒热途径的同源程度，设计了一种新型低温探针来创建冷伤害感觉的测定。该提案的初步数据显示，果蝇幼虫产生的一系列行为反应与对有毒热量和粗暴触摸的滚动反应不同。这些行为发生在大约75%的野生型幼虫中，并且是一致的和可复制的。基于先前对有害热的研究以及对有害冷刺激所观察到的明显不同的行为反应，我们假设对有害冷的感知需要一种单独的、特定类别的多树突感觉神经元和离子通道，并且这种反应在组织损伤后利用已知途径被敏感化。本应用程序中提出的实验将确定果蝇幼虫冷伤害感受所需的特定细胞和途径，从而进一步了解冷伤害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.