Behavioral Changes in Aging but Not Young Mice after Neonatal Exposure to the Polybrominated Flame Retardant DecaBDE

Abstract

BackgroundAfter several decades of commercial use, the flame-retardant chemicals polybrominated diphenyl ethers (PBDEs) and their metabolites are pervasive environmental contaminants and are detected in the human body. Decabrominated diphenyl ether (decaBDE) is currently the only PBDE in production in the United States.ObjectivesLittle is known about the health effects of decaBDE. In the present study we examined the effects of neonatal decaBDE exposure on behavior in mice at two ages.MethodsNeonatal male and female C57BL6/J mice were exposed to a daily oral dose of 0, 6, or 20 mg/kg decaBDE from postnatal days 2 through 15. Two age groups were examined: a cohort that began training during young adulthood and an aging cohort of littermates that began training at 16 months of age. Both cohorts were tested on a series of operant procedures that included a fixed-ratio 1 schedule of reinforcement, a fixed-interval (FI) 2-min schedule, and a light–dark visual discrimination.ResultsWe observed minimal effects on the light–dark discrimination in the young cohort, with no effects on the other tasks. The performance of the aging cohort was significantly affected by decaBDE. On the FI schedule, decaBDE exposure increased the overall response rate. On the light–dark discrimination, older treated mice learned the task more slowly, made fewer errors on the first-response choice of a trial but more perseverative errors after an initial error, and had lower latencies to respond compared with controls. Effects were observed in both dose groups and sexes on various measures.ConclusionsThese findings suggest that neonatal decaBDE exposure produces effects on behavioral tasks in older but not younger animals. The behavioral mechanisms responsible for the pattern of observed effects may include increased impulsivity, although further research is required.

Developmental Exposure to Polybrominated Diphenyl Ethers and Neurodevelopment

“…Effects did not vary by sex or mouse strain [40] and appeared to worsen with age, such that PBDE-related effects on altered spontaneous behavior and reduced habituation capabilities were more pronounced as the animals aged [34,36,37,38]. Effects on neurodevelopment were corroborated by others who found that in mice, perinatal PBDE exposure was associated with impaired learning and poorer functioning on memory tasks [41,42,43,44], altered locomotor activity, increased hyperactivity [45,46,47,48,49] and increased impulsivity, particularly in adult animals [50]. In rats, similar detrimental effects on attention and learning were also observed [43,51].…”

The Potential of Selected Brominated Flame Retardants to Affect Neurological Development

“…All of these studies except four (Dufault et al, 2005;Llansola et al, 2009;Cheng et al, 2009;Rice et al, 2009) examined motor activity. In the studies of Eriksson and Viberg, motor activity was often the only parameter assessed, although a few studies also examined spatial learning and memory using various maze apparatus.…”

“…Of these, nearly all (25 studies) evaluated motor activity. Four studies conducted neurobehavioral assessments but did not examine motor activity specifically (Dufault et al, 2005;Llansola et al, 2009;Cheng et al, 2009;Rice et al, 2009) and are not discussed further in this document. Of the studies that assessed effects on motor activity in animals, 15 also conducted additional neurobehavioral assessments, typically using a functional observational battery or maze apparatus.…”

Developmental neurotoxicants and the vulnerable male brain: a systematic review of suspected neurotoxicants that disproportionally affect males

“…After several decades of commercial use, PBDEs and their metabolites have become pervasive environmental contaminants and are detectable in the human body (Rice et al 2009). …”