Staples L G, McGregor I S, Apfelbach R, Hunt G E
School of Psychology, University of Sydney, Griffith Taylor Building (A18), NSW 2006, Australia.
Neuroscience. 2008 Feb 19;151(4):937-47. doi: 10.1016/j.neuroscience.2007.11.039. Epub 2007 Dec 4.
Cat odor and trimethylthiazoline (TMT, a component of fox feces) are two stimuli widely used in rodent models of fear and anxiety. Recent studies suggest that these odorants have distinct behavioral effects, raising questions as to whether TMT is a true "predator odor." Here we used c-Fos immunohistochemistry to compare patterns of neural activation produced by cat odor and TMT. Rats were exposed to either (1) three pieces of a collar that had been worn by a domestic cat, (2) three collar pieces impregnated with TMT (30 microl/piece), (3) three collar pieces impregnated with 4% formaldehyde (200 microl/piece, an acrid but non-predatory odor), or (4) three control (no odor) collar pieces. Odors were presented in a small well-ventilated plastic box. All odorants (cat odor, TMT and formaldehyde) produced increased defecation in rats compared with the control group, and formaldehyde exposure also decreased rearing. Cat odor increased contact with the stimulus relative to all other groups, while TMT increased contact compared with the formaldehyde and clean air groups. Only cat odor decreased grooming and elicited escape attempts. In addition, only cat odor caused pronounced activation of Fos in the accessory olfactory bulb and its projection areas, anterior olfactory nucleus, medial prefrontal cortex, striatum, and a medial hypothalamic circuit associated with defensive behavior. In contrast, the only areas activated by TMT were the internal granular layer of the main olfactory bulb and central amygdala, while both cat odor and TMT activated the glomeruli of the main olfactory bulb, piriform cortex, ventral orbital cortex and anterior cortical amygdala. Results indicate that the effects of cat odor and TMT are easily distinguished both behaviorally and at a neural level, and suggest that TMT lacks the "pheromone-like" quality of cat odor that engages key hypothalamic sites involved in defensive behavior.
猫的气味和三甲硫噻唑啉（TMT，狐狸粪便的一种成分）是恐惧和焦虑啮齿动物模型中广泛使用的两种刺激物。最近的研究表明，这些气味剂具有不同的行为效应，这引发了关于TMT是否是真正的“捕食者气味”的疑问。在这里，我们使用c-Fos免疫组织化学来比较猫气味和TMT产生的神经激活模式。将大鼠暴露于以下几种情况之一：（1）三块家猫佩戴过的项圈；（2）三块浸有TMT（30微升/块）的项圈；（3）三块浸有4%甲醛（200微升/块，一种刺鼻但无捕食性的气味）的项圈；或（4）三块对照（无气味）项圈。气味在一个小的通风良好的塑料盒中呈现。与对照组相比，所有气味剂（猫气味、TMT和甲醛）都使大鼠排便增加，暴露于甲醛还会减少大鼠的竖毛行为。与所有其他组相比，猫气味增加了与刺激物的接触，而与甲醛和清洁空气组相比，TMT增加了接触。只有猫气味减少了梳理行为并引发逃跑尝试。此外，只有猫气味导致副嗅球及其投射区域、前嗅核、内侧前额叶皮层、纹状体以及与防御行为相关的内侧下丘脑回路中Fos的明显激活。相比之下，TMT激活的唯一区域是主嗅球的内颗粒层和中央杏仁核，而猫气味和TMT都激活了主嗅球的肾小球、梨状皮层、眶腹侧皮层和前皮质杏仁核。结果表明，猫气味和TMT的作用在行为和神经水平上都很容易区分，这表明TMT缺乏猫气味那种能激活参与防御行为的关键下丘脑部位的“类信息素”特性。
