Direct contact with particulate matter increases oxidative stress in different brain structures.

INTRODUCTION

Several experimental and epidemiological studies have demonstrated the neurological adverse effects caused by exposure to air pollution, specifically in relation to pollutant particulate matter (PM). The objective of this study was to investigate the direct effect of PM in increased concentrations in different brain regions, as well as the mechanisms involving its neurotoxicity, by evaluating oxidative stress parameters in vitro.

METHODS

Olfactory bulb, cerebral cortex, striatum, hippocampus and cerebellum of rats were homogenized and incubated with PM < 2.5 μm of diameter (PM2.5) at concentrations of 3, 5 and 10 µg/mg of tissue. The oxidative damage caused by lipid peroxidation of these structures was determined by testing the thiobarbituric acid reactive species (TBA-RS). In addition, we measured the activity of antioxidant enzyme catalase (CAT) and superoxide dismutase (SOD).

RESULTS

All PM concentrations were able to damage the cerebellum and hippocampus, strongly enhancing the lipid peroxidation in both structures. PM incubation also decreased the CAT activity of the hippocampus, cerebellum, striatum and olfactory bulb, though it did not generate higher levels of lipid peroxidation in either of the last two structures. PM incubation did not alter any measurement of the cerebral cortex.

CONCLUSION

The cerebellum and hippocampus seem to be more susceptible than other brain structures to in vitro direct PM exposure assay and the oxidative stress pathway catalyzes the neurotoxic effect of PM exposure, as evidenced by high consumption of CAT and high levels of TBA-RS. Thus, PM direct exposure seems to activate toxic neurological effects.