Effects of decabromodiphenyl ether (BDE-209) on ultrasonic vocalizations emitted by rat pups during isolation.

Polybrominated diphenyl ethers (PBDEs) have been worldwide used as flame retardants. Among them, decabromodiphenyl ether (BDE-209) is the most applied and becomes ubiquitous in the environment and organisms. It can alter spontaneous behavior and affect the cholinergic system in rodents. Ultrasonic vocalizations (USVs) emitted by rat pups during isolation are widely employed as neurobehavioral indexes, and the cholinergic system supports their normal expression. However, whether BDE-209 can alter isolation USVs were unknown. In this study, BDE-209 was daily administered to mothers at 0, 500, or 1000 mg/kg b.w. from gestational day (GD) 15 to postnatal day (PND) 21. On PNDs 7, 10, 13, and 16, rat pups were individually isolated from mothers, and their USVs were recorded for 5 min after 5-min habituation and then analyzed. The results indicated that BDE-209 exposure can cause acoustic alterations in isolation USVs. The high-dose pups emitted USVs with shorter duration than the control pups did. Moreover, the percentages of frequency-modulated (FM) USVs in the high-dose pups were lower than those in the control pups. The mechanisms to alter acoustic characteristics of isolation USVs need further investigation. USV analysis is a useful method that provides neurobehavioral evidence.