Pamela Lein, Ph.D.
University of California, Davis
R21ES025570, R21ES026515, P30ES023513, T32ES007059
Early-life exposure to traffic-related air pollution (TRAP) impaired brain development in rats, according to an NIEHS-funded study. Studies in human populations have linked TRAP to increased risk for various neurodevelopmental disorders, but there is limited evidence for a causal relationship between TRAP and adverse neurodevelopment.
To assess real-world TRAP exposures, the researchers exposed male and female rats during gestation and early postnatal development to TRAP drawn directly from a traffic tunnel in Northern California, delivering it unchanged and in real time to an exposure chamber. They compared neurodevelopmental outcomes in TRAP-exposed rats with animals exposed to filtered air.
In male rats, TRAP exposure increased expression of the protein doublecortin, which is used as an indicator of production of new neurons in the brain. TRAP-exposed male rats also had a higher percentage of cycling neural cells than unexposed rats in a region of the brain hippocampus where adult neuron production occurs. Compared with unexposed females, researchers observed that exposed female rats exhibited decreased volume of the lateral ventricles — the largest brain cavities containing cerebrospinal fluid — and increased layer width of small neurons found in the cerebellum called granule cells. These altered patterns of cellular growth and neuron production in both males and females are common in various neurodevelopmental disorders and intellectual disabilities.
According to the authors, the findings suggest that exposure to real-world levels of TRAP during gestation and early postnatal development modulate neurodevelopment. Their findings corroborate epidemiological evidence of an association between TRAP exposure and increased risk of neurodevelopmental disorders.
Citation: Patten KT, González EA, Valenzuela A, Berg E, Wallis C, Garbow JR, Silverman JL, Bein KJ, Wexler AS, Lein PJ. 2020. Effects of early life exposure to traffic-related air pollution on brain development in juvenile Sprague-Dawley rats. Transl Psychiatry 10(1):166.