Abstract
BackgroundEffects of air pollution on neurotoxicity and behavioral alterations have been reported. The objective of this study was to investigate the pathophysiology caused by particulate matter (PM) in the brain. We examined the effects of traffic-related particulate matter with an aerodynamic diameter of < 1 μm (PM1), high-efficiency particulate air (HEPA)-filtered air, and clean air on the brain structure, behavioral changes, brainwaves, and bioreactivity of the brain (cortex, cerebellum, and hippocampus), olfactory bulb, and serum after 3 and 6 months of whole-body exposure in 6-month-old Sprague Dawley rats.ResultsThe rats were exposed to 16.3 ± 8.2 (4.7~ 68.8) μg/m3 of PM1 during the study period. An MRI analysis showed that whole-brain and hippocampal volumes increased with 3 and 6 months of PM1 exposure. A short-term memory deficiency occurred with 3 months of exposure to PM1 as determined by a novel object recognition (NOR) task, but there were no significant changes in motor functions. There were no changes in frequency bands or multiscale entropy of brainwaves. Exposure to 3 months of PM1 increased 8-isoporstance in the cortex, cerebellum, and hippocampus as well as hippocampal inflammation (interleukin (IL)-6), but not in the olfactory bulb. Systemic CCL11 (at 3 and 6 months) and IL-4 (at 6 months) increased after PM1 exposure. Light chain 3 (LC3) expression increased in the hippocampus after 6 months of exposure. Spongiosis and neuronal shrinkage were observed in the cortex, cerebellum, and hippocampus (neuronal shrinkage) after exposure to air pollution. Additionally, microabscesses were observed in the cortex after 6 months of PM1 exposure.ConclusionsOur study first observed cerebral edema and brain impairment in adult rats after chronic exposure to traffic-related air pollution.
Highlights
Effects of air pollution on neurotoxicity and behavioral alterations have been reported
Rats were continuously exposed to 24 weeks (6 months) of traffic-related PM1 during the study period
We further examined the Multiscale entropy (MSE) in rats, which showed no significant differences among the control, high-efficiency particulate air (HEPA), and PM1 groups after 3 and 6 months of exposure
Summary
Effects of air pollution on neurotoxicity and behavioral alterations have been reported. Exposure to 3 months of PM1 increased 8-isoporstance in the cortex, cerebellum, and hippocampus as well as hippocampal inflammation (interleukin (IL)-6), but not in the olfactory bulb. Observations from the U.S Department of Veterans Affairs Normative Aging Study cohort showed associations of traffic-related pollution and black carbon (BC) with cognition function [1]. Inflammatory responses in the lungs due to particulate air pollution are known to result in adverse cardiopulmonary health effects [7]; brain inflammation occurring due to air pollution is still poorly understood. Exposure to PM may increase oxidative stress and cerebral vascular injury, leading to systemic and local effects in different brain regions [9]
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