Binding of 2,3,7,8-tetrachlorodibenzo- p-dioxin to AH receptor in placentas from normal versus abnormal pregnancy outcomes

Binding of [ 3H]2,3,7,8-tetrachlorodibenzo- p-dioxin to AH receptor was characterized in cytosol from human placentas in which the pregnancy outcome was normal compared with pregnancies in which there was some adverse outcome (premature birth; intrauterine growth retardation; structural abnormality). No significant difference was detected between normal and adverse outcomes in the concentration of AH receptor sites (B max) nor in the affinity with which [ 3H]TCDD bound to the receptor (K d). Aryl hydrocarbon hydroxylase activity, a CYP1A1 enzyme regulated by the AH receptor, was elevated in placental microsomes from smokers; this elevation was associated with intrauterine growth retardation.