Neurochemical changes following a single dose of polybrominated diphenyl ether 47 in mice

Polybrominated diphenyl ethers (PBDEs) are commonly used as commercial flame retardants in a variety of products, including plastics and textiles. Previous studies in our laboratory, and in the literature, showed that exposure to a specific PBDE congener (PBDE 47) during a critical period of brain development may lead to developmental delays and hyperactivity in adulthood. To date, the underlying causes of these behavioral alterations are unknown, although in vitro studies linked PBDEs with potential alterations in neurotransmitter levels, particularly acetylcholine (ACh) and dopamine (DA). Alterations in DA function have also been noted in cases of hyperactivity in rodents and humans. The current study examined monoamine levels in male mice acutely exposed to corn oil vehicle or PBDE 47 (1, 10, or 30 mg/kg) on postnatal day (PND) 10. Animals were sacrificed on PND 15, PND 20, and in adulthood (131-159 days old). The cortex, striatum, and cerebellum were isolated and analyzed by high-performance liquid chromatography to determine the concentration of monoamines within each brain region. A statistically significant increase in DA levels was seen within the cortex, regardless of age, but only in the 10-mg/kg PBDE treatment group. While these effects did not show a monotonic dose response, we previously reported hyperactivity in littermates in the same dose group, but not at the lower or higher dose. Thus, early developmental exposure to PBDE 47 alters the levels of cortical DA in male mice, which may correlate with behavioral observations in littermates.