Does age matter? Comparison of neurobehavioral effects of paraquat exposure on postnatal and adult C57BL/6 mice

Epidemiological studies have revealed that environmentally relevant low levels of paraquat (PQ) exposure is listed on the etiology of neurological disorders such as Parkinson's disease (PD). The behavioral effects of PQ are of current interest, especially when exposure occurs in the period of early stage of life. To characterize whether and how age affects neurobehavioral performances of mice after PQ exposure, 21 days postnatal (PN21) and adult male C57BL/6 mice were daily administrated by oral gavage with 0mg/kg (saline, control), 5 mg/kg or 10 mg/kg of PQ for 28 consecutive days. Survival rate and body weight were analyzed. Subsequently, mice were subjected to Morris water maze tests (MWM). The results showed that mice exposed to PQ had significantly longer latencies than those in the control group, with a dose-dependent manner. Furthermore, PN21 mice tended to have longer latencies than adult mice in the same dose group. Our data suggested that PQ exposure induced significant learning and memory impairment and more severely in PN21 mice when compared with adult mice.