The aims of our present study were to establish a novel olfactory-based spatial\nlearning test and to examine the effects of exposure to nano-sized diesel exhaust-origin\nsecondary organic aerosol (SOA), a model environmental pollutant, on the learning performance\nin preweaning mice. Pregnant BALB/c mice were exposed to clean air, diesel exhaust (DE),\nor DE-origin SOA (DE-SOA) from gestational day 14 to postnatal day (PND) 10 in exposure\nchambers. On PND 11, the preweaning mice were examined by the olfactory-based spatial\nlearning test. After completion of the spatial learning test, the hippocampus from each mouse\nwas removed and examined for the expressions of neurological and immunological markers\nusing real-time RT-PCR. In the test phase of the study, the mice exposed to DE or DE-SOA\ntook a longer time to reach the target as compared to the control mice. The expression levels\nof neurological markers such as the N-methyl-D-aspartate (NMDA) receptor subunits NR1 and NR2B, and of immunological markers such as TNF-, COX2, and Iba1 were significantly\nincreased in the hippocampi of the DE-SOA-exposed preweaning mice as compared to the\ncontrol mice. Our results indicate that DE-SOA exposure in utero and in the neonatal period\nmay affect the olfactory-based spatial learning behavior in preweaning mice by modulating\nthe expressions of memory functionââ?¬â??related pathway genes and inflammatory markers in\nthe hippocampus.
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