Tin-Tin Win-Shwe: Center for Environmental Health Sciences, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan. tin.tin.win.shwe@nies.go.jp.
Chaw Kyi-Tha-Thu: Division of Life Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570, Japan. chawchaw25@gmail.com.
Yadanar Moe: Division of Life Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570, Japan. yadanarmoe.91@gmail.com.
Fumihiko Maekawa: Center for Environmental Health Sciences, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan. fmaekawa@nies.go.jp.
Rie Yanagisawa: Center for Environmental Health Sciences, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan. yanagisawa.rie@nies.go.jp.
Akiko Furuyama: Center for Environmental Risk Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan. kawagoe@nies.go.jp.
Shinji Tsukahara: Division of Life Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570, Japan. stsuka@mail.saitama-u.ac.jp.
Yuji Fujitani: Center for Environmental Risk Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan. fujitani.yuji@nies.go.jp.
Seishiro Hirano: Center for Environmental Risk Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan. seishiro@nies.go.jp.
The aims of our present study were to establish a novel olfactory-based spatial learning test and to examine the effects of exposure to nano-sized diesel exhaust-origin secondary organic aerosol (SOA), a model environmental pollutant, on the learning performance in preweaning mice. Pregnant BALB/c mice were exposed to clean air, diesel exhaust (DE), or DE-origin SOA (DE-SOA) from gestational day 14 to postnatal day (PND) 10 in exposure chambers. On PND 11, the preweaning mice were examined by the olfactory-based spatial learning test. After completion of the spatial learning test, the hippocampus from each mouse was removed and examined for the expressions of neurological and immunological markers using real-time RT-PCR. In the test phase of the study, the mice exposed to DE or DE-SOA took a longer time to reach the target as compared to the control mice. The expression levels of neurological markers such as the -methyl-d-aspartate (NMDA) receptor subunits NR1 and NR2B, and of immunological markers such as TNF-α, COX2, and Iba1 were significantly increased in the hippocampi of the DE-SOA-exposed preweaning mice as compared to the control mice. Our results indicate that DE-SOA exposure and in the neonatal period may affect the olfactory-based spatial learning behavior in preweaning mice by modulating the expressions of memory function-related pathway genes and inflammatory markers in the hippocampus.
