Developmental exposure to PBDE 209: Sex, neuroprotein and neurobehavioural analyses

Abstract

Polybrominated diphenyl ethers (PBDEs) are used in large quantities as flame-retardants in polymers products.Newborns and toddlers can be indirectly and directly exposed to PBDEs during a period of critical rapid brain development. The present study was undertaken to investigate neurotoxic effects after neonatal exposure to PBDE 209 on sex differences, cognitive function, neuroproteins and altered susceptibility to toxicants in adults. 3-day-old NMRI mice were exposed to PBDE 209 (2,2´,3,3´,4,4´,5,5´,6,6´-decaBDE at 0, 1.4, 6.0 and 14 µmol/kg bw). At 2 months of age male mice were exposed to paraoxon (0.25 mg/kg bw, every 2nd day for 7 days) and female mice exposed to nicotine (80 µg nicotine base/kg bw). At the age of 2 and 4 months mice were observed for spontaneous behaviour, before and after adult exposure to paraoxon (male) and nicotine (female). Male mice aged 5 and 7 months were observed for memory and learning. Neuroproteins CaMKII, GAP-43, synaptophysin and tau in cerebral cortex and hippocampus from 7-months old male and female mice were analyzed. The present study shows that neonatal exposure to PBDE 209 can induce developmental neurobehavioural defects in both male and female mice. Neonatal exposure to PBDE 209 also caused increased susceptibility in adult mice to paraoxon and nicotine. All these effects were dose response related. Further, neonatal exposure to PBDE 209 caused persistent defects in memory and learning in adult male mice and increased levels of important neuroproteins e.g. tau in adult male and female mice.