Abstract
Diesel exhaust particle (DEP) is a major constituent of particulate matter in the atmosphere, and secondary organic aerosol (SOA) is formed as a result of oxidation of volatile components of primary exhaust. We have reported that inhalation exposure to DE-SOA from fetal stage to infancy may affect some social behaviors and spatial learning abilities. Recently, some reports have indicated that there is an association exists between air pollution and mental disorders. However, little is known about effects of DE-SOA exposure on anxiety and depressive symptoms. In this study, we examined the effects of exposure to DE-SOA from fetal stage to infancy on anxiety and emotion level. Exposure was carried out using a BALB/c mouse on a schedule of 5 hours a day for 5 days per week from embryonic day 14 to postnatal day 21. The treatment group consisted of clean air (Control), DE-SOA, DE and GAS groups. We performed anxiety/depression like behavior tests (light/dark transition test, forced swimming test). As a result, no effect on anxiety-like behaviors measured in light/dark transition test and depression-like behavior measured in forced swimming test was observed. Taken together, exposure to DE-SOA from fetal stage to lactation stage did not have a significant effect on postnatal anxiety and depression. Our findings indicate that DE or DE-SOA exposure during early developmental stages may not affect at least development of central nervous system, which regulates anxiety and emotion level. However, oxidative stress and microglia activation were found in the hypothalamus of those mice. We suggest that DE-SOA exposure during brain developmental period may induce changes in molecular level but not functional level in the present study.
