Negative effects of ultrafine particle exposure during forced exercise on the expression of Brain-Derived Neurotrophic Factor in the hippocampus of rats

Exercise improves cognitive function, and Brain-Derived Neurotrophic Factor (BDNF) plays a key role in this process. We recently reported that particulate matter (PM) exposure negatively contributed to the exercise-induced increase in human serum BDNF concentration. Furthermore, PM exposure is associated with neuroinflammation and cognitive decline. The aim of this study was to investigate the effect of exposure to ultrafine particles (UFP) during a single bout of forced exercise on the expression of inflammatory (IL1α, IL1β, TNF, IL6, NOS2, NOS3) and oxidative stress (NFE2L2)-related genes, as well as BDNF in the brain of rats. Four groups (n = 6/group) of Wistar rats were exposed for 90 min to one of the following exposure regimes: UFP + exercise, UFP + rest, ambient air + exercise, ambient air + rest (control). Hippocampus, olfactory bulb and prefrontal cortex were collected 24 h after exposure. Gene expression changes were analyzed with real-time PCR. In the condition ambient air + exercise, hippocampal expression of BDNF and NFE2L2 was up-regulated, while the expression of IL1α and NOS3 in the prefrontal cortex and IL1α in the olfactory bulb was down-regulated compared to the control. In contrast, gene expression in the condition UFP + exercise did not differ from the control. In the condition UFP + rest, hippocampal expression of NFE2L2 was down-regulated and there was a trend toward down-regulation of BDNF expression compared to the control. This study shows a negative effect of UFP exposure on the exercise-induced up-regulation of BDNF gene expression in the hippocampus of rats.

► We exposed 4 groups of rats to exercise or rest in ambient air or UFP-polluted air.
► Gene expression in hippocampus, prefrontal cortex and olfactory bulb was analyzed.
► Exercise in ambient air increased hippocampal BDNF expression.
► Hippocampal BDNF expression did not increase following exercise in UFP-polluted air.