Neurobehavioral effects of concurrent exposure to cesium-137 and paraquat during neonatal development in mice

As a result of nuclear power plants accidents such as Chernobyl or Fukushima, some people were exposed to external and internal ionizing radiation (IR). Human brain is highly sensitive to IR during fetal and postnatal period when the molecular processes are not completely finished. Various studies have shown that exposure to low doses of IR causes a higher incidence of cognitive impairment. On the other hand, in industrialized countries, people are daily exposed to a number of toxicant pollutants. Exposure to environmental chemicals, such as paraquat (PQ), may potentiate the toxic effects induced by radiation on brain development. In this study, we evaluated the cognitive effects of concomitant exposure to low doses of internal radiation (137Cs) and PQ during neonatal brain development. At the postnatal day 10 (PND10), two groups of mice (C57BL/6J) were exposed to 137Cs (4000 and 8000 Bq/kg) and/or PQ (7 mg/kg). To investigate the spontaneous behavior, learning, memory capacities and anxiety, behavioral tests were conducted in the offspring at two months of age. The results showed that cognitive functions were not significantly affected when 137Cs or PQ were administered alone. However, alterations in the working memory and anxiety were detected in mice exposed to 137Cs combined with PQ.