Optogenetically induced olfactory stimulation in Drosophila larvae reveals the neuronal basis of odor-aversion behavior
Optogenetically induced olfactory stimulation in Drosophila larvae reveals the neuronal basis of odor-aversion behavior
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DOI：
10.3389/fnbeh.2010.00027
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发表时间：
2010-01-01
影响因子：
3
通讯作者：
Stoertkuhl, Klemens F.
中科院分区：
文献类型：
--
作者：
Bellmann, Dennis;Richardt, Arnd;Stoertkuhl, Klemens F.
嗅觉刺激诱导果蝇幼虫的气味引导的爬行行为，其特征是吸引或排斥反应。为了了解导致这些方向的潜在过程，我们通过完整神经元网络内的光激活来刺激单个嗅觉受体神经元（ORN）。使用 Gal4-UAS 系统，两种光诱导蛋白，光敏阳离子通道视紫红质-2 (ChR-2) 或光敏腺苷酸环化酶 (Pac α) 在幼虫嗅觉系统的所有或单个 ORN 中表达。蓝光刺激引起这些神经元的激活，最终产生气味刺激的错觉。在趋光性测定中测试幼虫朝向或远离光源的方向。在这里，我们表明，在盲目的norpA突变幼虫中，表达携带Or33b或Or45a受体的Pac alpha的ORN的激活会诱导远离光的驱避行为。相反，大多数 ORN 的光激活会诱导光的吸引力。有趣的是，在野生型幼虫中，Or33b 和 Or45a 的两个配体，分别是乙酸辛酯和丙酸乙酯，被发现会引起逃逸反应。因此，我们结合光和气味刺激来分析表达ORN的Or33b和Or45a的功能。我们表明，幼虫嗅觉系统包含用于驱避气味的指定神经元通路，并且特定类别 ORN 的激活已经决定了嗅觉回避行为。
Olfactory stimulation induces an odor-guided crawling behavior of Drosophila melanogaster larvae characterized by either an attractive or a repellent reaction. In order to understand the underlying processes leading to these orientations we stimulated single olfactory receptor neurons (ORNs) through photo-activation within an intact neuronal network. Using the Gal4-UAS system two light inducible proteins, the light-sensitive cation channel channelrhodopsin-2 (ChR-2) or the light-sensitive adenylyl cyclase (Pac alpha) were expressed in all or in individual ORNs of the larval olfactory system. Blue light stimulation caused an activation of these neurons, ultimately producing the illusion of an odor stimulus. Larvae were tested in a phototaxis assay for their orientation toward or away from the light source. Here we show that activation of Pac alpha expressing ORNs bearing the receptors Or33b or Or45a in blind norpA mutant larvae induces a repellent behavior away from the light. Conversely, photo-activation of the majority of ORNs induces attraction towards the light. Interestingly, in wild type larvae two ligands of Or33b and Or45a, octyl acetate and propionic ethylester, respectively, have been found to cause an escape reaction. Therefore, we combined light and odor stimulation to analyze the function of Or33b and Or45a expressing ORNs. We show that the larval olfactory system contains a designated neuronal pathway for repellent odorants and that activation of a specific class of ORNs already determines olfactory avoidance behavior.