Impact on murine neurodevelopment of early-life exposure to airborne ultrafine carbon nanoparticles

Abstract The effects of ultrafine particle (UFP) inhalation on neurodevelopment, especially during critical windows of early life, remain largely unexplored. The specific time windows during which exposure to UFP might be the most detrimental remain poorly understood. Here, we studied early-life exposure to clean ultrafine carbonaceous particles (UFPC) and neurodevelopment and central nervous system function in offspring. Pregnant wild-type C57BL/6J mice were either sham-exposed (HEPA-filtered air) or exposed to clean ultrafine carbonaceous particles at a concentration of 438 ± 72 μg/m³ (mean ± SD) and a count median diameter of 49 ± 2 nm (CMD ± GSD) via whole-body exposure for four hours per day. For prenatal exposure, mice were exposed for two consecutive days in two exposure periods, while the postnatal exposure was conducted for four consecutive days in two exposure periods. The mice were divided into four groups: (i) sham, (ii) only prenatal exposure, (iii) only postnatal exposure, and (iv) both prenatal and postnatal exposure. Neurodevelopmental behaviour was assessed throughout the life of the offspring using a functional observation battery. Early-life UFPC-exposed offspring exhibited altered anxiety-related behaviour in the open field test, with exclusively postnatally exposed offspring (567 ± 120 s) spending significantly more time within the border zone of the arena compared to the sham group (402 ± 73 s), corresponding to an increase of approximately 41% (p < 0.05). The behavioural alterations remained unaffected by olfactory function or maternal behaviour. Mice with both prenatal and postnatal exposure did not show this effect. No discernible impact on developmental behavioural reflexes was evident. Early life exposure to UFPC, particularly during the early postnatal period, may lead to developmental neurotoxicity, potentially resulting in complications for the central nervous system later in life. The current data will support future studies investigating the possible effects and characteristics of nanoparticle-based toxicity.