Perinatal exposure to diesel exhaust origin secondary organic aerosol induces autism-like behavior in rats
Abstract Background: Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impaired social communication, poor social interactions and repetitive behaviors. The exact cause and mechanism of autism remains unknown. Both genetic and environmental factors may involve in ASD. In this study, we used diesel exhaust (DE) origin secondary organic aerosol (DE-SOA) as environmental pollutants. DE-SOA was generated by oxidative reaction of mixing DE with ozone. The aim of present study is to examine autism-like behaviors and related gene expressions in rats exposed to DE-SOA perinatally. Sprague-Dawley pregnant rats were exposed to clean air (control), DE and DE-SOA in the exposure chamber for 5 h per day (from 10:00 pm to 3:00 am), 5 days a week excluding weekends from gestational day 14 to postnatal day 21 with their pups. At postnatal day 21, the male and female offspring rats were allocated into three different groups as follows: 1) rats exposed to clean filtered air; 2) rats exposed to DE; 3) rats exposed to DE-SOA. Social behaviors were investigated at 10~13-weeks-old rats using a 3-chambered social behavior test, social dominance tube test and marble burying test. Prefrontal cortex was collected to examine neurological and immunological markers, and glutamate concentration, using real-time RT-PCR and ELISA methods. Results: DE-SOA-exposed male and female rats showed poor sociability and social novelty preference, socially dominant behavior and increased repetitive behavior compared with the control rats. The mRNA expression levels of serotonin receptor (5-HT(5B)) and brain-derived neurotrophic factor (BDNF) were down-regulated whereas interleukin 1 b (IL-b), and heme oxygenase 1 (HO-1) were upregulated in the prefrontal cortex of male and female rats exposed to DE-SOA compared to the control rats. Glutamate concentration was increased significantly in the prefrontal cortex of both male and female rats exposed to DE-SOA.Conclusion: Our results indicate that perinatal exposure to DE-SOA may induce autism-like behavior in rats by modulating neurological and immunological markers in the prefrontal cortex.