Effects of perinatal exposure to a polybrominated diphenyl ether (PBDE 99) on mouse neurobehavioural development

Polybrominated diphenyl ethers (PBDEs), a class of widely used flame retardants, are extensively diffused in the environment as shown by several studies on sentinel animal species, as well as humans. Of particular concern are the reported high levels of PBDEs in human milk, as almost no information is available on their potential effects on developing organisms. We investigated the effects of perinatal PBDE exposure on mouse neurobehavioural development. 2,2',4,4,5-pentabromodiphenylether (PBDE 99; 0.6, 6 and 30 mg/kg per day) was administered daily to CD-1 Swiss females by gavage from gestational day (GD) 6 to postnatal day (PND) 21. Aroclor 1254 (A1254; 6 mg/ kg per day), a PCB mixture, was administered following the same schedule and served as a positive controL The PBDE 99 medium dose had an effect on litter viability. Sensori-motor development analysis (PNDs 2-20) revealed a delayed appearance of climbing response in the PBDE 99 high-dose group. On PND 11, the homing test revealed a trend for treated animals, particularly the A1254 group, to be more active than controls. This activity level alteration was strongly increased on PNDs 34 and 60 in an open-field arena. On PND 60, treated mice showed also an altered thigmotaxis, spending more time in the centre of the arena than controls. At adulthood, A1254 treated mice were still hyperactive, whereas the PBDE 99 groups tended to be hypoactive. These findings showed that perinatal exposure to PBDE 99 produces several behavioural alterations and that its effects are not always similar to those of A1254. The possibility of exposure of neonates to PBDEs warrants further studies to characterise their developmental neurotoxicity.