Wittenburg N, Baumeister R
Genzentrum, Ludwig-Maximilians-Universität, Feodor-Lynen-Strasse 25, D-81377 Munich, Germany.
Proc Natl Acad Sci U S A. 1999 Aug 31;96(18):10477-82. doi: 10.1073/pnas.96.18.10477.
Upon perception of a noxious stimulus, an organism executes defense mechanisms, such as escape responses. The molecular basis of these mechanisms is poorly understood. In this paper we show that upon exposure to noxious temperature, Caenorhabditis elegans reacts by a withdrawal reflex. To analyze this thermal avoidance behavior, we developed a laser-based assay to quantify the response. The escape reflex can be observed in 98% of the adult animals, but is not executed in animals in diapause. The thermal avoidance response differs significantly from the thermotaxis behavior that is based on the perception of physiological temperature. It involves different neurons and is influenced by mutations in distinct genes. As in mammals, the strength of the thermal avoidance response is increased by application of capsaicin, the pungent ingredient in chili peppers. We find that thermal avoidance is strongly reduced in mutants affecting the neural transmission modulated by glutamate and neuropeptides as well as in mutants affecting the structure and function of sensory neurons. We suggest that the study of this nociceptive behavior in C. elegans can be used to understand the genetic and molecular basis of thermal nociception.
在感知到有害刺激时，生物体执行防御机制，如逃避反应。这些机制的分子基础尚不清楚。在本文中，我们表明，暴露于有害温度下时，秀丽隐杆线虫会通过退缩反射做出反应。为了分析这种热回避行为，我们开发了一种基于激光的测定方法来量化反应。在98%的成年动物中可以观察到逃避反射，但处于滞育状态的动物不会执行。热回避反应与基于生理温度感知的趋温行为有显著差异。它涉及不同的神经元，并受到不同基因中突变的影响。与哺乳动物一样，辣椒素（辣椒中的辛辣成分）的应用会增强热回避反应的强度。我们发现，影响由谷氨酸和神经肽调节的神经传递的突变体以及影响感觉神经元结构和功能的突变体中，热回避能力会大大降低。我们建议，对秀丽隐杆线虫这种伤害感受行为的研究可用于理解热伤害感受的遗传和分子基础。
