title: Tetrachlorodibenzo-p-dioxin exposure alters radial arm maze performance and hippocampal morphology in female AhR mice.
abstract: Perinatal exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has been reported to alter spatial learning in rats tested on a radial arm maze (RAM). TCDD is believed to exert most of its effects through binding to the aryl hydrocarbon receptor (AhR). To determine whether the AhR mediates TCDD-induced alterations in spatial learning, we tested male and female AhR-knockout (AhR-/-), heterozygous (AhR+/-) and wild-type (AhR+/+) mice on the RAM. AhR+/- male and female mice were time mated, and treated dams were dosed with 5 microg TCDD/kg body weight on day 13 of gestation. When offspring reached adulthood, male and female AhR+/+, AhR+/- and AhR-/- mice from TCDD-exposed and unexposed litters were tested on the eight-arm RAM. After testing, we examined hippocampal morphology as visualized by the Timm's silver sulfide stain. TCDD-exposed female AhR+/- mice made more errors than their respective controls on the RAM and exhibited a decrease in the size of the intra- and infrapyramidal mossy fiber (IIP-MF) field of the hippocampus. None of the other TCDD-exposed groups differed from their respective control groups with regard to maze performance or hippocampal morphology. The reduction of IIP-MF field indicates a possible morphological basis for the learning deficit that was observed in the female AhR+/- mice. It is hypothesized that the effect of TCDD exposure is AhR dependent and that TCDD may alter GABAergic activity in the hippocampus of female mice during development.
authors.affiliation: Department of Veterinary Biosciences, University of Illinois at Urbana-Champaign, Urbana, IL 61802, USA.
authors.forename: B E
authors.initials: BE
authors.lastname: Powers
authors.forename: T-M
authors.initials: TM
authors.lastname: Lin
authors.forename: A
authors.initials: A
authors.lastname: Vanka
authors.forename: R E
authors.initials: RE
authors.lastname: Peterson
authors.forename: J M
authors.initials: JM
authors.lastname: Juraska
authors.forename: S L
authors.initials: SL
authors.lastname: Schantz
mesh_terms: D000818:Animals; D005260:Female; D006624:Hippocampus / Q000187:drug effects* / Q000473:pathology; D008297:Male; D018782:Maze Learning / Q000187:drug effects*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D019599:Mossy Fibers, Hippocampal / Q000187:drug effects / Q000473:pathology; D000072317:Polychlorinated Dibenzodioxins / Q000633:toxicity*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D018336:Receptors, Aryl Hydrocarbon / Q000172:deficiency / Q000187:drug effects*; D013028:Space Perception / Q000187:drug effects; D013723:Teratogens / Q000633:toxicity*
chemical_list: D000072317:Polychlorinated Dibenzodioxins; D018336:Receptors, Aryl Hydrocarbon; D013723:Teratogens