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Behabioral effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin in male Wistar rats.

Kimihiro Yamashita, Yasuko Sakurai-Yamashita* and Kohtaro Taniyama*.
Department of Environmental Coservation, Faculty of Environmental Studies,@Nagasaki University and *Department of Pharmacology, Nagasaki Univerrsity@School of Medicine.

2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is considered to be one of the most potent environmental endocrine disruptors. TCDD has been demonstrated to be a potent carcinogen and have immunoptoxic effects. It is still uncertain, however, whether dioxins have also toxic properties in the central nervous system. The present study was designed to investigate the toxicity of subchronic treatment of TVDD in the central nervous system of male Wistar rats. Rats were received oral administrations of TCDD (1ƒÊg/kg/week) from 8 weeks-old to 28 weeks-old, and locomotor activities, food consumption and water intakes were measured. The TCDD-treated rats were significantly reduced in the gains of body weight compared to vehicle-controls. Under 12 hour-light/dark condition, the TCDD-treated rats exhibited higher locomotor activities in all experimental periods, and that was stastically significant at 16-20 weeks after the treatment, without altering circadian rhythm. Food and water intakes were not different between the groups. these result suggest that TCDD may affect in a central nervous system to occur hyperactivity in rats even in adulthood.