Department of Regenerative Medicine and Cell Therapy, Institute of Neurobiology, Biomedical Research Center, Slovak Academy of Sciences, Košice, Slovak Republic.
Department of Anatomy, Histology and Physiology, University of Veterinary Medicine and Pharmacy in Kosice, Košice, Slovak Republic.
Stress. 2020 Nov;23(6):678-687. doi: 10.1080/10253890.2020.1828337. Epub 2020 Oct 14.
The main and accessory olfactory bulbs (MOB and AOB) are unique in that they produce new neurons throughout adulthood. Despite the recent knowledge about the involvement of postnatally generated cells in several aspects of olfaction, the functional role of these neurons is still not sufficiently understood. The function of newly generated olfactory bulb neurons is primarily investigated in relation to activities related to smell. Stress-induced activation of new olfactory neurons has not yet been studied. Thus, our work was aimed to investigate whether a stressful event, such as maternal separation (MS) can induce Fos expression in postnatally-born neurons in the MOB and AOB. Rat pups were exposed to single maternal separation (SMS) for 2 h at the postnatal days: P7, P14, and P21. Quantification of immunohistochemically labeled Fos + cells revealed that exposure to SMS in different age stages during the first postnatal month stimulates activity in cells of individual MOB/AOB layers in an age-dependent manner. In order to find out whether newly generated cells in the MOB/AOB could express Fos protein as a response to SMS, newborn rats were administrated with the marker of proliferation, bromodeoxyuridine (BrdU) at P0, and three weeks later (at P21) colocalization of Fos and BrdU in the neurons of the MOB and AOB was assessed. Quantitative analysis of BrdU/Fos double-labeled cells showed that Fos is expressed only in a small number of postnatally generated cells within the MOB/AOB. Our results indicate that postnatally generated MOB/AOB neurons are less sensitive to stress caused by MS than preexisting ones. LAY SUMMARY Our results showed that single maternal separation (SMS) is a stressful event that in age-dependent manner stimulates cellular activity in the main and accessory olfactory bulb (AOB) - the structures dedicated to odor information processing. The low level of Fos expression in newborn neurons of the main and accessory bulb indicates that postnatally generated cells are less sensitive to neonatal stress than preexisting neurons.
嗅球（MOB 和 AOB）的主要和辅助嗅觉球在成年后产生新神经元，这是独特的。尽管最近的知识表明，出生后产生的细胞参与了嗅觉的几个方面，但这些神经元的功能作用仍未得到充分理解。新产生的嗅球神经元的功能主要与与嗅觉相关的活动有关。应激诱导的新生嗅神经元的激活尚未得到研究。因此，我们的工作旨在研究应激事件（如母体分离（MS））是否会诱导 MOB 和 AOB 中出生后神经元表达 Fos。新生大鼠在出生后的第 7、14 和 21 天接受单次母体分离（SMS）2 小时。免疫组织化学标记的 Fos+细胞的定量分析表明，在出生后第一个月的不同年龄阶段暴露于 SMS 以年龄依赖的方式刺激单个 MOB/AOB 层的细胞活性。为了确定 MOB/AOB 中的新生细胞是否可以作为 SMS 的反应表达 Fos 蛋白，新生大鼠在 P0 时给予增殖标志物溴脱氧尿苷（BrdU），三周后（在 P21 时）评估 MOB 和 AOB 神经元中 Fos 和 BrdU 的共定位。BrdU/Fos 双标记细胞的定量分析表明，Fos 仅在 MOB/AOB 中的少数出生后产生的细胞中表达。我们的结果表明，出生后产生的 MOB/AOB 神经元对 MS 引起的应激的敏感性低于预先存在的神经元。
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