In numerous mammalian species, the nose harbors several compartments populated by chemosensory cells. Among them, the Grueneberg ganglion (GG) located in the anterior nasal region comprises sensory neurons activated by given substances. In rodents, in which the GG has been best studied, these chemical cues mainly include heterocyclic compounds released by predators or by conspecifics. Since some of these substances evoke fear- or stress-associated responses, the GG is considered as a detector for alerting semiochemicals. In fact, certain behavioral and physiological reactions to alarm pheromones and predator-secreted kairomones are attenuated in the absence of a functional GG. Intriguingly, GG neurons are also stimulated by cool temperatures. Moreover, ambient temperatures modulate olfactory responsiveness in the GG, indicating that cross-talks exist between the transduction pathways mediating chemo- and thermosensory signaling in this organ. In this context, exploring the relevant molecular cascades has demonstrated that some chemosensory transduction elements are also crucial for thermosensory signaling in the GG. Finally, for further processing of sensory information, axons of GG neurons project to the olfactory bulb of the brain where they innervate distinct glomerular structures belonging to the enigmatic necklace glomeruli. In this review, the stimuli activating GG neurons as well as the underlying transduction pathways are summarized. Because these stimuli do not exclusively activate GG neurons but also other sensory cells, the biological relevance of the GG is discussed, with a special focus on the role of the GG in detecting alarm signals.

中文翻译：

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Grueneberg 神经节：嗅觉和热感觉器官中的信号转导和编码，参与检测警报信息素和捕食者分泌的 kairomones

在许多哺乳动物物种中，鼻子有几个由化学感应细胞填充的隔室。其中，位于鼻前区的 Grueneberg 神经节 (GG) 包括由给定物质激活的感觉神经元。在啮齿类动物中，GG 得到了最好的研究，这些化学线索主要包括捕食者或同种动物释放的杂环化合物。由于这些物质中的一些会引起与恐惧或压力相关的反应，因此 GG 被认为是警告信息化学物质的检测器。事实上，在没有功能性 GG 的情况下，对警报信息素和捕食者分泌的 kairomones 的某些行为和生理反应会减弱。有趣的是，低温也会刺激 GG 神经元。此外，环境温度会调节 GG 的嗅觉反应能力，表明在该器官中介导化学和热传感信号的转导通路之间存在串扰。在这种情况下，探索相关的分子级联已经证明一些化学感应转导元件对于 GG 中的热感应信号传导也至关重要。最后，为了进一步处理感觉信息，GG 神经元的轴突投射到大脑的嗅球，在那里它们支配属于神秘项链肾小球的不同肾小球结构。在这篇综述中，总结了激活 GG 神经元的刺激以及潜在的转导途径。由于这些刺激不仅会激活 GG 神经元，还会激活其他感觉细胞，因此讨论了 GG 的生物学相关性，特别关注 GG 在检测警报信号中的作用。