BINDING OF 2,3,7-8-TETRACHLORODIBENZO-P-DIOXIN TO AH RECEPTOR IN PLACENTAS FROM NORMAL VERSUS ABNORMAL PREGNANCY OUTCOMES

Binding of [H-3]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 a dverse outcome (premature birth; intrauterine growth retardation; stru ctural abnormality). No significant difference was detected between no rmal and adverse outcomes in the concentration of AH receptor sites (B -max) nor in the affinity with which [H-3]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. (C) 1997 Elsevier Science Ltd.