Sulkowski Mikolaj J, Kurosawa Mathieu S, Cox Daniel N
School of Systems Biology, George Mason University, Manassas, Virginia 20120, USA.
Biol Bull. 2011 Dec;221(3):300-6. doi: 10.1086/BBLv221n3p300.
The ability to perceive and avoid harmful substances or stimuli is key to an organism's survival. The neuronal cognate of the perception of pain is known as nociception, and the reflexive motion to avoid pain is termed the nocifensive response. As the nocifensive response is an ancient and evolutionarily conserved behavioral response to nociceptive stimuli, it is amenable to study in relatively simple and genetically tractable model systems such as Drosophila. Recent studies have taken advantage of the useful properties of Drosophila larvae to begin elucidating the neuronal connectivity and molecular machinery underlying the nocifensive response. However, these studies have primarily utilized the third-instar larval stage, and many mutations that potentially influence nociception survive only until earlier larval stages. Here we characterize the nocifensive responses of Drosophila throughout larval development and find dramatic changes in the nature of the behavior. Notably, we find that prior to the third instar, larvae are unable to perform the characteristic "corkscrew-like roll" behavior. Also, we identify an avoidance behavior consistent with a nocifensive response that is present immediately after larval hatching, representing a paradigm that may be useful in examining mutations with an early lethal phenotype.
感知并避开有害物质或刺激的能力是生物体生存的关键。对疼痛的感知在神经元层面被称为伤害感受，而避免疼痛的反射性动作则被称为伤害防御反应。由于伤害防御反应是对伤害性刺激的一种古老且在进化上保守的行为反应，因此适合在相对简单且具有遗传易处理性的模型系统（例如果蝇）中进行研究。最近的研究利用了果蝇幼虫的有用特性，开始阐明伤害防御反应背后的神经元连接和分子机制。然而，这些研究主要利用的是三龄幼虫阶段，许多可能影响伤害感受的突变仅存活到更早的幼虫阶段。在这里，我们描述了果蝇在整个幼虫发育过程中的伤害防御反应，并发现了行为性质的显著变化。值得注意的是，我们发现三龄之前的幼虫无法做出典型的“螺旋状翻滚”行为。此外，我们识别出一种与伤害防御反应一致的回避行为，这种行为在幼虫孵化后立即出现，代表了一种可能有助于研究具有早期致死表型突变的范例。
