Behavioral and thyroid effects of in utero and lactational exposure of Sprague–Dawley rats to the polybrominated diphenyl ether mixture DE71

Abstract

Exposure of rodents during gestation and lactation to polybrominated diphenyl ethers (PBDEs) has been reported to disrupt neurobehavioral function in offspring, as well as to disrupt thyroid function. To assess this we evaluated development and behavior after gestational and lactational exposure to the technical PBDE mixture DE71. Pregnant Sprague–Dawley rats were exposed to 0, 0.3, 3.0 or 30mg/kg/day of DE71 from gestation day 1 to postnatal day (PND) 21 and were assessed on a wide range of behavioral functions from early postnatal period until old age (PND 450). DE71 exposure decreased thyroid hormone levels (T3 and T4) in mothers and offspring with offspring being more sensitive that mothers. Developmental landmarks, neuromotor function, anxiety, learning and memory were not affected by DE71 at any age. DE71 produced small changes in motor activity rearing only at PND 110 but not at any other age and no other activity measure was altered by DE71. Cholinergic sensitivity measured by nicotine-stimulated motor activity was not affected by perinatal DE71 exposure. Acoustic startle responses were potentiated by DE71 at PND 90 indicating delayed effects on sensory reactivity. Habituation was measured in motor activity tests at five ages but was not altered by DE71 at any age. Habituation measured in startle tests was also not affected by exposure to DE71. For thyroid hormone levels at PND 21, the lowest adverse effect level was 3.0mg/kg. Few behavioral effects were observed and the lowest adverse effect level was 30mg/kg. Our results confirm that DE71 produces transient effects on thyroid hormone levels but does not result in learning or motor impairment and does not alter non-associative learning (habituation).