Deranged spontaneous behaviour and decrease in cholinergic muscarinic receptors in hippocampus in the adult rat, after neonatal exposure to the brominated flame-retardant, 2,2′,4,4′,5-pentabromodiphenyl ether (PBDE 99)

Polybrominated diphenyl ethers (PBDEs), which are used as flame-retardants, have recently been shown to be increasing in the environment and in human milk. We have recently reported that neonatal exposure to PBDEs, including 2,2′,4,4′,5-pentaBDE (PBDE 99), can induce persistent aberrations in spontaneous behaviour and also affect learning and memory functions and nicotinic cholinergic receptors in the adult mice. The present study indicates that spontaneous behaviour, along with the cholinergic system during its developing stage, can be targets for PBDEs in the rat as well. Neonatal oral exposure of male Sprague-Dawley rats, on postnatal day 10, to 0.8, 8.0, and 16 mg PBDE 99/kg body weight, was shown to disrupt normal spontaneous behaviour in a dose-response related manner at 2 months of age. Also, the animals of the present study showed a decrease in density of muscarinic cholinergic receptors in hippocampus, at an adult age. These findings show similarities to observations made from neonatal exposure of mice to PBDE 99, 2,2′,4,4′,5,5′-hexaBDE (PBDE 153) and certain PCBs, compounds shown to affect both spontaneous behaviour and the cholinergic system.