title: Chronic postnatal DE-71 exposure: effects on learning, attention and thyroxine levels.
abstract: Polybrominated diphenyl ethers (PBDEs) are ubiquitous, bioaccumulative flame retardants. Much remains to be learned about their developmental toxicological properties, particularly with regards to chronic exposure. In two experiments, male Long-Evans rats ingested the commercial pentaBDE mixture DE-71 from birth onward, first through the milk of lactating dams (who ingested 5 or 7.5 mg DE-71/day in a custom-mixed chow), then directly via chow consumption (at a dose of 3 or 4.5 mg/day). Control rats consumed the same brand of chow without DE-71. As adults, the rats were assessed for learning and attention using a series of five-choice serial reaction time tasks. A challenge with the muscarinic cholinergic antagonist scopolamine (0, 0.01, 0.03, or 0.05 mg/kg injected s.c.) was conducted on the final attention task. Serum total thyroxine (T4) levels were obtained at the end of testing. Total T4 was significantly lower in both DE-71 groups than in controls. Visual discrimination learning was unaffected by DE-71, but rats ingesting 4.5 mg/day DE-71 demonstrated significant impairments in sustained attention and inhibitory control, as evidenced by increased premature responding and decreased accuracy of responding in Attention Task 1. However, the DE-71-exposed rats did not respond differentially to the effects of scopolamine on attention compared to controls. These effects of chronic developmental DE-71 exposure differ from effects seen with brief postnatal exposure, suggesting that more research needs to be done on the more environmentally relevant chronic exposure model.
authors.affiliation: Laboratory of Behavioral Neurotoxicology, Department of Psychology, The Colorado College, Colorado Springs, CO 80903, USA. Ldriscoll@coloradocollege.edu
authors.forename: L L
authors.initials: LL
authors.lastname: Driscoll
authors.forename: A M
authors.initials: AM
authors.lastname: Gibson
authors.forename: A
authors.initials: A
authors.lastname: Hieb
mesh_terms: D000818:Animals; D001288:Attention / Q000187:drug effects*; D001835:Body Weight / Q000187:drug effects; D004193:Discrimination Learning / Q000187:drug effects*; D004347:Drug Interactions; D005260:Female; D005411:Flame Retardants / Q000633:toxicity*; D055768:Halogenated Diphenyl Ethers / Q000008:administration & dosage / Q000633:toxicity*; D008297:Male; D008895:Milk, Human; D018727:Muscarinic Antagonists / Q000633:toxicity; D051381:Rats; D020318:Rats, Long-Evans; D012601:Scopolamine / Q000008:administration & dosage / Q000494:pharmacology; D013974:Thyroxine / Q000097:blood*
chemical_list: D005411:Flame Retardants; D055768:Halogenated Diphenyl Ethers; D018727:Muscarinic Antagonists; C086401:pentabromodiphenyl ether; D012601:Scopolamine; D013974:Thyroxine