Ambient levels of concentrated PM2.5 affects cell kinetics in adrenal glands: an experimental study in mice

Abstract

We evaluated the effects of air pollution on the adrenal cortex using 30 female mice divided into two groups of fifteen animals each. One group was conditioned daily in a chamber with exposure to particulate matter (PM) 2.5 μm (GExp). Animals were exposed on daily basis in an ambient particles concentrator during the period of time enough to reach an accumulated dose of 600 μg/m³, which corresponds to a 24-h exposure of 25 μg/m³ that approximates to the annual mean of PM2.5 in São Paulo. The other group was allocated to another chamber with filtered air (GCrt). After euthanasia, the adrenals underwent histological processing and immunohistochemistry staining for Ki-67 and cleaved caspase-3. Histomorphometry of the adrenal glands in GExp showed increased thickness of the zona glomerulosa, while in GCrt; the adrenal glands from GExp had higher Ki-67 immunostaining scores in the zona reticularis than those from GCrt. The adrenal from GExp showed higher cleaved caspase-3 immunoreactivity in the zona fasciculata than the unexposed group (GCrt). The homeostasis index indicated higher cell proliferation in the zona glomerulosa and zona reticularis in GExp than in GCrt. Our data indicate that PM2.5 air pollution induces alterations on cell kinetics in mouse adrenal glands.

Chinese abstract

我们评估空气污染对肾上腺皮质的影响, 包括30只雌性小鼠分为两组, 每组15只。一组每日暴露于含颗粒物(PM) 2.5 μm的房间(GExp)。这些动物每天暴露于环境微粒集中器中, 在足够的时间达到累计剂量600μg/m³, 这相当于24小时暴露于25μg/m³, 这近似圣保罗的年平均PM2.5。另一组处于过滤空气的另一房间中(GCrt)。安乐死后, 肾上腺行组织学切片和Ki-67、活性caspase-3免疫组织化学染色。与GCrt组相比, GExp组中的肾上腺的组织形态显示球状带增厚, 肾上腺在网状带有更高的Ki-67免疫染色分数, 肾上腺在束状带有更高的caspase-3免疫反应活性；动态平衡指数表明GExp组比GCrt组中球状带和网状带有更高的细胞增殖。我们的研究表明PM2.5空气污染引起鼠肾上腺细胞动力学的改变。

Keywords:

• Adrenal
• mouse
• PM2.5
• traffic
• urban pollution

Acknowledgements

The authors would like to thank Prof Maria Lúcia Flynn for language revision.

Declaration of interest

The authors report no conflicts of interest in this study.