Laboratory of Neuronal Plasticity and Neurorepair, Institute for Neuroscience of Castile and Leon (INCyL), University of Salamanca, C/ Pintor Fernando Gallego, 1, 37007, Salamanca, Spain.
Institute of Biomedical Research of Salamanca, IBSAL, 37007, Salamanca, Spain.
Sci Rep. 2020 Dec 9;10(1):21533. doi: 10.1038/s41598-020-78499-5.
The interneurons of the olfactory bulb (OB) are characterized by the expression of different calcium-binding proteins, whose specific functions are not fully understood. This is the case of one of the most recently discovered, the secretagogin (SCGN), which is expressed in interneurons of the glomerular and the granule cell layers, but whose function in the olfactory pathway is still unknown. To address this question, we examined the distribution, generation and activity of SCGN-positive interneurons in the OB of two complementary models of olfactory impairments: Purkinje Cell Degeneration (PCD) and olfactory-deprived mice. Our results showed a significant increase in the density of SCGN-positive cells in the inframitral layers of olfactory-deprived mice as compared to control animals. Moreover, BrdU analyses revealed that these additional SCGN-positive cells are not newly formed. Finally, the neuronal activity, estimated by c-Fos expression, increased in preexisting SCGN-positive interneurons of both deprived and PCD mice -being higher in the later- in comparison with control animals. Altogether, our results suggest that the OB possesses different compensatory mechanisms depending on the type of alteration. Particularly, the SCGN expression is dependent of olfactory stimuli and its function may be related to a compensation against a reduction in sensory inputs.
嗅球（OB）的中间神经元的特征是表达不同的钙结合蛋白，其特定功能尚未完全了解。这是最近发现的一种蛋白，即分泌素（SCGN），它在肾小球和颗粒细胞层的中间神经元中表达，但在嗅觉通路中的功能仍不清楚。为了解决这个问题，我们研究了两种嗅觉损伤模型（浦肯野细胞退化（PCD）和嗅觉剥夺小鼠）中 SCGN 阳性中间神经元在 OB 中的分布、产生和活性。我们的结果表明，与对照组动物相比，嗅觉剥夺小鼠的嗅小球下区的 SCGN 阳性细胞密度显著增加。此外，BrdU 分析表明，这些额外的 SCGN 阳性细胞不是新形成的。最后，通过 c-Fos 表达估计的神经元活性在两种剥夺和 PCD 小鼠的预先存在的 SCGN 阳性中间神经元中增加 - 在后者中比对照组更高。总的来说，我们的结果表明，OB 具有不同的补偿机制，具体取决于改变的类型。特别是，SCGN 的表达依赖于嗅觉刺激，其功能可能与对感觉输入减少的补偿有关。
