Abstract

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.

摘要

主要和辅助嗅球（MOB和AOB）的独特之处在于，它们在整个成年期都会产生新的神经元。尽管最近有关嗅觉的几个方面涉及出生后生成的细胞的知识，但这些神经元的功能作用仍未得到足够的了解。主要针对与气味有关的活动研究了新产生的嗅球神经元的功能。尚未对应激诱导的新嗅觉神经元激活进行研究。因此，我们的工作旨在调查应激事件（例如母体分离（MS））是否可以诱导MOB和AOB中出生后神经元的Fos表达。在出生后的第2天，将大鼠幼崽分别暴露于母体分离（SMS）：P7，P14和P21。免疫组织化学标记的Fos +细胞的定量显示，出生后第一个月在不同年龄阶段接触SMS会以年龄依赖性方式刺激单个MOB / AOB层细胞的活性。为了确定MOB / AOB中新产生的细胞是否可以表达Fos蛋白作为对SMS的反应，新生大鼠在P0时被给予增殖标记，即溴脱氧尿苷（BrdU），三周后（在P21时）进行共定位评估了MOB和AOB神经元中Fos和BrdU的水平。BrdU / Fos双标记细胞的定量分析表明，Fos仅在MOB / AOB内的少量产后生成的细胞中表达。我们的结果表明，出生后生成的MOB / AOB神经元对MS引起的压力的敏感度低于现有神经元。

• 图层摘要

• 我们的结果表明，单身母亲分离（SMS）是一个压力事件，它以年龄相关的方式刺激主嗅球（AOB）–专门用于气味信息处理的结构中的细胞活性。在主球和副球的新生神经元中，Fos表达水平较低，表明出生后生成的细胞对新生应激的敏感性低于先前存在的神经元。