Freezing to the predator odor 2,4,5 dihydro 2,5 trimethylthiazoline (TMT) is disrupted by olfactory bulb removal but not trigeminal deafferentation
Freezing to the predator odor 2,4,5 dihydro 2,5 trimethylthiazoline (TMT) is disrupted by olfactory bulb removal but not trigeminal deafferentation
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DOI：
10.1016/j.bbr.2013.06.034
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发表时间：
2013-09-15
影响因子：
2.7
通讯作者：
Rosen, Jeffrey B.
中科院分区：
文献类型：
--
作者：
Ayers, Luke W.;Asok, Arun;Rosen, Jeffrey B.
2，4，5-二氢-2，5-三甲基噻唑啉（TMT）是赤狐肛门分泌物中的一种人工合成成分，对大鼠和小鼠具有明显的防御作用。TMT与其他捕食者气味不同，因为它是一种单分子，可以大量合成，并且在实验环境中暴露剂量高度可控。TMT已经成为研究嗅觉刺激介导先天恐惧行为的大脑机制的流行工具。然而，TMT作为生物学相关嗅觉刺激物的这一观点受到了以下建议的挑战，即气味由于其刺激性特性而引起恐惧行为，为了解决这一批评，我们的实验室测量了大鼠在暴露于2种气味时的冻结行为，（TMT和丁酸）和H2O（无气味控制）后，手术横断三叉神经或消融嗅球。我们的研究结果（实验1）表明，冻结行为TMT需要一个完整的嗅觉系统，所示的损失冻结嗅球去除。实验二发现三叉神经切断后大鼠对TMT的冻结行为正常，提示嗅觉系统介导了TMT的冻结行为。实验1，包括上下文恐惧条件反射的复制显示，减少冻结行为是由于无法嗅球消融大鼠冻结（实验3）。两者合计，这些研究结果支持TMT的作用，作为一个生态相关的捕食者气味有用的无条件的恐惧，是通过嗅觉介导的实验，而不是伤害性感受。(C)2013爱思唯尔有限公司版权所有。
2,4,5 dihydro 2,5 trimethylthiazoline (TMT) is a synthesized component of red fox anal secretions that reliably elicits defensive behaviors in rats and mice. TMT differs from other predator odors because it is a single molecule, it can be synthesized in large quantities, and the dose for exposure is highly controllable in an experimental setting. TMT has become a popular tool for studying the brain mechanisms that mediate innate fear behavior to olfactory stimuli. However, this view of TMT as a biologically relevant olfactory stimulus has been challenged by suggestions that the odor elicits fear behavior due to its irritating properties, presumably working through a nociceptive mechanism.To address this criticism our lab measured freezing behavior in rats during exposures to 2 odors (TMT and butyric acid) and H2O (no odor control) following either surgical transection of the trigeminal nerves or ablation of the olfactory bulbs. Our findings (Experiment 1) indicate that freezing behavior to TMT requires an intact olfactory system, as indicated by the loss of freezing following olfactory bulb removal. Experiment 2 revealed that rats with trigeminal nerve transection freeze normally to TMT, suggesting the olfactory system mediates this behavior to TMT. A replication of Experiment 1 that included contextual fear conditioning revealed that the decreased freezing behavior was not due to an inability of olfactory bulb ablated rats to freeze (Experiment 3). Taken together, these findings support TMT's role as an ecologically relevant predator odor useful in experiments of unconditioned fear that is mediated via olfaction and not nociception. (C) 2013 Elsevier B.V. All rights reserved.