Abstract
Diesel exhaust particles are a major component of ambient particulate matter, and concern about the health effects of exposure to ambient particulate matter is growing. Previously, we found that in utero exposure to diesel exhaust affected locomotor activity and motor coordination, but there are also indications that such exposure may contribute to increased aggression in offspring. Therefore, the aim of the present study was to test the effects of prenatal diesel exhaust exposure on social isolation-induced territorial aggression. Pregnant mice were exposed to low concentrations of diesel exhaust (DE; mass concentration of 90 μg/m3: DE group: n = 15) or clean air (control group: n = 15) for 8 h/day during gestation. Basal locomotion of male offspring was measured at 10 weeks of age. Thereafter, male offspring were individually housed for 2 weeks and subsequently assessed for aggression using the resident−intruder test at 12 weeks of age, and blood and brain tissue were collected from the male offspring on the following day for measuring serum testosterone levels and neurochemical analysis. There were no significant differences in locomotion between control and DE-exposed mice. However, DE-exposed mice showed significantly greater social isolation-induced territorial aggressive behavior than control mice. Additionally, socially-isolated DE-exposed mice expressed significantly higher concentrations of serum testosterone levels than control mice. Neurochemical analysis revealed that dopamine levels in the prefrontal cortex and nucleus accumbens were higher in socially isolated DE-exposed mice. Serotonin levels in the nucleus accumbens, amygdala, and hypothalamus were also lower in the socially isolated DE-exposed mice than in control mice. Thus, even at low doses, prenatal exposure to DE increased aggression and serum testosterone levels, and caused neurochemical changes in male socially isolated mice. These results may have serious implications for pregnant women living in regions with high levels of traffic-related air pollution.
Highlights
Diesel exhaust particles (DEPs), which are derived from diesel exhaust (DE) engines [1], are among the most abundant air pollutants in urban environments
No evidence concerning the relationship between exposure to particulate matter in air pollution and increased aggressive behavior has yet been reported, except for a study reporting the effects of prenatal cigarette smoke exposure [27], which increased the number of attacks and altered DA and 5-HT levels in the striatum and prefrontal cortex
We found that maternal exposure to DE resulted in higher levels of DA and its metabolites (DOPAC, homovanillic acid (HVA)) in the prefrontal cortex and nucleus accumbens of socially isolated male offspring than in control mice
Summary
Diesel exhaust particles (DEPs), which are derived from diesel exhaust (DE) engines [1], are among the most abundant air pollutants in urban environments. Ultrafine particles may have greater toxic effects on the central nervous system, in structures such as the olfactory bulb, cerebral cortex, and hippocampus, than larger particulate matter [10, 11]. We have previously reported that maternal exposure to DE caused accumulation of DEP-like substances in the brains of the offspring, and that these particles induced apoptosis [13]. Prenatal exposure to DE and DEPs causes behavioral dysfunction, such as leaning/memory and motor-coordination deficits, in male mice [14,15,16]. These studies have typically used higher exposures to DE than are encountered in most environments, and the effect of more typical exposures remains unclear
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call