Acharya Namrata, Wiesel Eric, Selcho Mareike, Ehmann Nadine, Lamberty Marius, Hansson Bill S, Wicher Dieter, Kittel Robert J
Department of Animal Physiology, Faculty of Life Sciences, Leipzig University, Leipzig, Germany.
Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, Jena, Germany.
Front Cell Neurosci. 2025 Aug 26;19:1579821. doi: 10.3389/fncel.2025.1579821. eCollection 2025.
Olfactory sensory neurons (OSNs) detect odours at a wide range of intensities. In , volatile compounds bind to specific odorant receptors (ORs), which tune the sensitivity of chemoreception. To test whether additional mechanisms underlie odour-specific neuronal processing, we analysed the spatial distribution of ORs in dendrites and investigated OSN synapses in the antennal lobe, the first relay station of the olfactory pathway. Here, we studied the molecular structure and plasticity of the presynaptic active zone (AZ), the specialized site of neurotransmitter release. We focused on a highly sensitive OSN type that expresses the receptor Or56a and is exclusively activated by geosmin, an odorant signalling ecologically harmful microorganisms. Our results uncover a differential arrangement of dendritic ORs and core AZ proteins in alarm odour-detecting Or56a compared to conventional food-odour detecting OSNs. Interestingly, the data also show that Or56a OSNs display a limited capacity for homeostatic plasticity in response to a genetic reduction of presynaptic release probability. We hypothesise that this feature reflects the basal tuning of geosmin-sensing neurons towards maximum levels of performance.
嗅觉感觉神经元（OSNs）能在广泛的强度范围内检测气味。在体内，挥发性化合物与特定的气味受体（ORs）结合，这些受体调节化学感受的敏感性。为了测试是否有其他机制参与气味特异性神经元处理过程，我们分析了树突中ORs的空间分布，并研究了嗅觉通路的第一个中继站——触角叶中的OSN突触。在这里，我们研究了突触前活性区（AZ）的分子结构和可塑性，这是神经递质释放的特化位点。我们聚焦于一种高度敏感的OSN类型，它表达受体Or56a，并且仅被土臭素激活，土臭素是一种指示生态有害微生物的气味信号。我们的结果揭示了与传统的检测食物气味的OSNs相比，检测警报气味的Or56a在树突状ORs和核心AZ蛋白上的差异排列。有趣的是，数据还表明，Or56a OSNs在应对突触前释放概率的基因降低时，表现出有限的稳态可塑性能力。我们推测，这一特征反映了土臭素感知神经元对最大性能水平的基础调节。
