Peri- and postnatal exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin: effects on physiological development, reflexes, locomotor activity and learning behaviour in Wistar rats.
Effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the development of rat offspring were studied after administration of a loading dose of 300 or 1000 ng TCDD/kg body wt on day 19 of pregnancy, followed by weekly maintenance doses of 120 or 400 ng TCDD/kg body wt. The dose regimens led to a fluctuation of average TCDD concentrations in the liver of the offspring of 4.9-14.9 ng/g (TCDD1000/400 group) or 1.4-6.3 ng/g (TCDD300/120 group) during the course of the experiment. In both TCDD-exposed groups the body weight of the offspring was significantly lower on postnatal day 7 (PND 7); in the high dose group from PND 7 to PND 31. Some landmarks of postnatal development were retarded in the exposed groups; in particular, the vaginal opening was delayed for several days in both TCDD-exposed groups. The TCDD-exposed animals revealed a reduced ability to remain on a rotating rod. During reflex testing, the rate of successfully responding animals was higher in the exposed groups. No statistically significant differences in the locomotor activity between controls and TCDD-exposed offspring were detectable under our experimental conditions. In a discrimination learning test no effects on the learning ability were found. However, TCDD-exposed offspring showed an increase in unanswered trials during critical phases of the task. They also exhibited increased locomotor activity in a novel environment; prior to an amphetamine challenge dose of 1 mg/kg body weight. Amphetamine-induced activity was decreased in a dose-dependent manner.
Thiel
R
R
Institut für Toxikologie und Embryopharmakologie, FU Berlin, Germany.
Koch
E
E
Ulbrich
B
B
Chahoud
I
I
D000818:Animals; D000831:Animals, Newborn / Q000254:growth & development; D001522:Behavior, Animal / Q000187:drug effects*; D001835:Body Weight / Q000187:drug effects; D005133:Eye Movements / Q000187:drug effects; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007858:Learning / Q000187:drug effects*; D008099:Liver / Q000737:chemistry; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D000072317:Polychlorinated Dibenzodioxins / Q000032:analysis / Q000633:toxicity*; D051381:Rats; D017208:Rats, Wistar / Q000254:growth & development*; D012018:Reflex / Q000187:drug effects*; D013737:Testis
D000072317:Polychlorinated Dibenzodioxins