title: In utero and lactational exposure to low doses of chlorinated and brominated dioxins induces deficits in the fear memory of male mice.
abstract: Environmental-level in utero and lactational exposures to dioxins have been considered to affect brain functions of offspring. Here, we determined whether in utero and lactational exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and 2,3,7,8-tetrabromodibenzo-p-dioxin (TBDD), at the dose that does not harm the dams, affects the acquisition and retention of fear memory in mouse offspring. Pregnant C57BL/6J mice were administered by gavages TCDD or TBDD at a dose of 0 or 3.0 microg/kg body weight on gestation day 12.5, and their male offspring were examined for their behavior in adulthood. In the fear conditioning, a paired presentation of tone and foot shock was repeated three times, and retention tests for contextual and auditory fear memory were carried out 1 and 24h after the fear conditioning. Groups of mice that were exposed to TCDD and TBDD in utero and via lactation showed deficits in the contextual and auditory retention tests at 1 and 24h retention intervals. The present results suggest that maternal exposure to a low dose of TCDD or TBDD disrupts the functions of memory and emotion in male mouse offspring, and that the developmental toxicities of these chemicals are similar to each other.
authors.affiliation: Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Asahi
authors.initials: A
authors.lastname: Haijima
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Endo
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Wataru
authors.initials: W
authors.lastname: Miyazaki
authors.forename: Masaki
authors.initials: M
authors.lastname: Kakeyama
authors.forename: Chiharu
authors.initials: C
authors.lastname: Tohyama
mesh_terms: D000818:Animals; D001942:Breast Feeding / Q000009:adverse effects*; D003214:Conditioning, Classical / Q000187:drug effects; D004147:Dioxins / Q000008:administration & dosage / Q000633:toxicity*; D004785:Environmental Pollutants / Q000008:administration & dosage / Q000633:toxicity*; D005239:Fear / Q000523:psychology*; D005260:Female; D007774:Lactation; D008297:Male; D008568:Memory / Q000187:drug effects*; D051379:Mice; D008810:Mice, Inbred C57BL; D000072317:Polychlorinated Dibenzodioxins / Q000008:administration & dosage / Q000633:toxicity*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000523:psychology*
chemical_list: D004147:Dioxins; D004785:Environmental Pollutants; D000072317:Polychlorinated Dibenzodioxins; C066841:2,3,7,8-tetrabromodibenzo-4-dioxin