Neonatal exposure to the brominated flame-retardant, 2,2′,4,4′,5-pentabromodiphenyl ether, decreases cholinergic nicotinic receptors in hippocampus and affects spontaneous behaviour in the adult mouse

Abstract

Polybrominated diphenyl ethers (PBDEs) are used as flame-retardants and have recently been shown to increase in the environment and in human milk. We have recently reported that neonatal exposure to 2,2′,4,4′,5-pentaBDE (PBDE 99) can induce persistent aberrations in spontaneous behaviour and also affect learning and memory functions in the adult animal. The present study indicates that the cholinergic system, in its developing stage, can be a target for PBDEs. Neonatal oral exposure of male NMRI mice, on postnatal day 10, to 2,2′,4,4′,5-pentaBDE (12 mg/kg body weight) was shown to decrease the density of cholinergic nicotinic receptors in hippocampus, at an adult age. These findings show similarities to observations made from neonatal exposure to 2,2′,4,4′,5,5′-hexaBDE, PCBs and nicotine, compounds shown to affect cholinergic nicotinic receptors. The animals of the present study also showed disrupted spontaneous behaviour, and the highest dose that did not cause any significant behavioural disruption was 0.4 mg 2,2′,4,4′,5-pentaBDE/kg b.w.