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Title: Tetrachlorodibenzo-p-dioxin exposure alters radial arm maze performance and hippocampal morphology in female AhR mice.

Authors: Powers, B E; Lin, T-M; Vanka, A; Peterson, R E; Juraska, J M; Schantz, S L

Published In Genes Brain Behav, (2005 Feb)

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.

PubMed ID: 15660668 Exiting the NIEHS site

MeSH Terms: Animals; Female; Hippocampus/drug effects*; Hippocampus/pathology; Male; Maze Learning/drug effects*; Mice; Mice, Inbred C57BL; Mice, Knockout; Mossy Fibers, Hippocampal/drug effects; Mossy Fibers, Hippocampal/pathology; Polychlorinated Dibenzodioxins/toxicity*; Pregnancy; Prenatal Exposure Delayed Effects*; Receptors, Aryl Hydrocarbon/deficiency; Receptors, Aryl Hydrocarbon/drug effects*; Space Perception/drug effects; Teratogens/toxicity*

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